50b10b8a90
Adjust two-word substitution parameters to be one word only to reduce possible ambiguity.
2220 lines
61 KiB
Plaintext
2220 lines
61 KiB
Plaintext
<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table.sgml,v 1.21 2000/04/12 04:40:03 thomas Exp $
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Postgres documentation
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-->
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<refentry id="SQL-CREATETABLE">
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<refmeta>
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<refentrytitle id="sql-createtable-title">
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CREATE TABLE
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</refentrytitle>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>
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CREATE TABLE
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</refname>
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<refpurpose>
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Creates a new table
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</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<refsynopsisdivinfo>
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<date>2000-03-25</date>
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</refsynopsisdivinfo>
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<synopsis>
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CREATE [ TEMPORARY | TEMP ] TABLE <replaceable class="PARAMETER">table</replaceable> (
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<replaceable class="PARAMETER">column</replaceable> <replaceable class="PARAMETER">type</replaceable>
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[ NULL | NOT NULL ] [ UNIQUE ] [ DEFAULT <replaceable class="PARAMETER">value</replaceable> ]
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[<replaceable>column_constraint_clause</replaceable> | PRIMARY KEY } [ ... ] ]
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[, ... ]
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[, PRIMARY KEY ( <replaceable class="PARAMETER">column</replaceable> [, ...] ) ]
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[, CHECK ( <replaceable class="PARAMETER">condition</replaceable> ) ]
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[, <replaceable>table_constraint_clause</replaceable> ]
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) [ INHERITS ( <replaceable>inherited_table</replaceable> [, ...] ) ]
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</synopsis>
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<refsect2 id="R2-SQL-CREATETABLE-1">
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<title>
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Inputs
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</title>
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<para>
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<variablelist>
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<varlistentry>
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<term>TEMPORARY</term>
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<listitem>
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<para>
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The table is created only for this session, and is
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automatically dropped on session exit.
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Existing permanent tables with the same name are not visible
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while the temporary table exists.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">table</replaceable></term>
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<listitem>
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<para>
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The name of a new class or table to be created.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">column</replaceable></term>
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<listitem>
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<para>
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The name of a column.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">type</replaceable></term>
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<listitem>
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<para>
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The type of the column. This may include array specifiers.
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Refer to the <citetitle>PostgreSQL User's Guide</citetitle> for
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further information about data types and arrays.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>DEFAULT <replaceable class="PARAMETER">value</replaceable></term>
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<listitem>
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<para>
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A default value for a column.
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See the DEFAULT clause for more information.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>column_constraint_clause</replaceable></term>
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<listitem>
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<para>
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The optional column constraint clauses specify a list of integrity
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constraints or tests which new or updated entries must satisfy for
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an insert or update operation to succeed. Each constraint
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must evaluate to a boolean expression. Although <acronym>SQL92</acronym>
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requires the <replaceable class="PARAMETER">column_constraint_clause</replaceable>
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to refer to that column only, <productname>Postgres</productname>
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allows multiple columns
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to be referenced within a single column constraint.
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See the column constraint clause for more information.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>table_constraint_clause</replaceable></term>
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<listitem>
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<para>
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The optional table CONSTRAINT clause specifies a list of integrity
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constraints which new or updated entries must satisfy for
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an insert or update operation to succeed. Each constraint
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must evaluate to a boolean expression. Multiple columns
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may be referenced within a single constraint.
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Only one PRIMARY KEY clause may be specified for a table;
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PRIMARY KEY <replaceable>column</replaceable>
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(a table constraint) and PRIMARY KEY (a column constraint) are
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mutually exclusive..
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See the table constraint clause for more information.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>INHERITS <replaceable class="PARAMETER">inherited_table</replaceable></term>
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<listitem>
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<para>
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The optional INHERITS clause specifies a collection of table
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names from which this table automatically inherits all fields.
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If any inherited field name appears more than once,
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<productname>Postgres</productname>
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reports an error.
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<productname>Postgres</productname> automatically allows the created
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table to inherit functions on tables above it in the inheritance
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hierarchy.
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<note>
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<title>Aside</title>
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<para>
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Inheritance of functions is done according
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to the conventions of the Common Lisp Object System (CLOS).
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</para>
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</note>
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect2>
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<refsect2 id="R2-SQL-CREATETABLE-2">
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<title>
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Outputs
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</title>
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<para>
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<variablelist>
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<varlistentry>
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<term><computeroutput>
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CREATE
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</computeroutput></term>
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<listitem>
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<para>
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Message returned if table is successfully created.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><computeroutput>
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ERROR
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</computeroutput></term>
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<listitem>
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<para>
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Message returned if table creation failed.
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This is usually accompanied by some descriptive text, such as:
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<computeroutput>
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ERROR: Relation '<replaceable class="parameter">table</replaceable>' already exists
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</computeroutput>
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which occurs at runtime, if the table specified already exists
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in the database.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><computeroutput>
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ERROR: DEFAULT: type mismatched
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</computeroutput></term>
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<listitem>
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<para>
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If data type of default value doesn't match the
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column definition's data type.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect2>
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</refsynopsisdiv>
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<refsect1 id="R1-SQL-CREATETABLE-1">
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<title>
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Description
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</title>
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<para>
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<command>CREATE TABLE</command> will enter a new class or table
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into the current data base. The table will be "owned" by the user issuing the
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command.
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</para>
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<para>
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Each <replaceable class="PARAMETER">type</replaceable>
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may be a simple type, a complex type (set) or an array type.
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Each attribute may be specified to be non-null and
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each may have a default value, specified by the
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<xref linkend="R1-SQL-DEFAULTCLAUSE-1-TITLE" endterm="R1-SQL-DEFAULTCLAUSE-1-TITLE">.
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</para>
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<para>
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<note>
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<para>
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As of Postgres version 6.0, consistant array dimensions within an
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attribute are not enforced. This will likely change in a future
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release.
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</para>
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</note>
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</para>
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<para>
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The optional INHERITS
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clause specifies a collection of class names from which this class
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automatically inherits all fields. If any inherited field name
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appears more than once, Postgres reports an error. Postgres automatically
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allows the created class to inherit functions on classes above it in
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the inheritance hierarchy. Inheritance of functions is done according
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to the conventions of the Common Lisp Object System (CLOS).
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</para>
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<para>
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Each new table or class <replaceable class="PARAMETER">table</replaceable>
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is automatically created as a type. Therefore, one or more instances
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from the class are automatically a type and can be used in
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<xref linkend="sql-altertable-title" endterm="sql-altertable-title">
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or other <command>CREATE TABLE</command> statements.
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</para>
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<para>
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The new table is created as a heap with no initial data.
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A table can have no more than 1600 columns (realistically,
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this is limited by the fact that tuple sizes must
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be less than 8192 bytes), but this limit may be configured
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lower at some sites. A table cannot have the same name as
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a system catalog table.
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</para>
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</refsect1>
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<refsect1 id="R1-SQL-DEFAULTCLAUSE-1">
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<title id="R1-SQL-DEFAULTCLAUSE-1-TITLE">
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DEFAULT Clause
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</title>
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<para>
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<synopsis>
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DEFAULT <replaceable class="PARAMETER">value</replaceable>
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</synopsis>
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</para>
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<refsect2 id="R2-SQL-DEFAULTCLAUSE-1">
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<title>
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Inputs
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</title>
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<para>
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<variablelist>
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<varlistentry>
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<term><replaceable class="parameter">value</replaceable></term>
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<listitem>
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<para>
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The possible values for the default value expression are:
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<itemizedlist>
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<listitem>
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<simpara>
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a literal value
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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a user function
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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a niladic function
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</simpara>
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</listitem>
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</itemizedlist>
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect2>
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<refsect2 id="R2-SQL-DEFAULTCLAUSE-2">
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<title>
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Outputs
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</title>
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<para>
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None.
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</para>
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</refsect2>
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<refsect2 id="R2-SQL-DEFAULTCLAUSE-3">
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<title>
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Description
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</title>
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<para>
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The DEFAULT clause assigns a default data value to a column
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(via a column definition in the CREATE TABLE statement).
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The data type of a default value must match the column definition's
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data type.
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</para>
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<para>
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An INSERT operation that includes a column without a specified
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default value will assign the NULL value to the column
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if no explicit data value is provided for it.
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Default <replaceable class="parameter">literal</replaceable> means
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that the default is the specified constant value.
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Default <replaceable class="parameter">niladic-function</replaceable>
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or <replaceable class="parameter">user-function</replaceable> means
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that the default
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is the value of the specified function at the time of the INSERT.
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</para>
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<para>
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There are two types of niladic functions:
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<variablelist>
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<varlistentry>
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<term>niladic USER</term>
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<listitem>
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<variablelist>
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<varlistentry>
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<term>CURRENT_USER / USER</term>
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<listitem>
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<simpara>See CURRENT_USER function</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>SESSION_USER</term>
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<listitem>
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<simpara>not yet supported</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>SYSTEM_USER</term>
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<listitem>
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<simpara>not yet supported</simpara>
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</listitem>
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</varlistentry>
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</variablelist>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>niladic datetime</term>
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<listitem>
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<variablelist>
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<varlistentry>
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<term>CURRENT_DATE</term>
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<listitem>
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<simpara>See CURRENT_DATE function</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>CURRENT_TIME</term>
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<listitem>
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<simpara>See CURRENT_TIME function</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>CURRENT_TIMESTAMP</term>
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<listitem>
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<simpara>See CURRENT_TIMESTAMP function</simpara>
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</listitem>
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</varlistentry>
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</variablelist>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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In the current release (v7.0), <productname>Postgres</productname>
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evaluates all default expressions at the time the table is defined.
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Hence, functions which are "non-cacheable" such as
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<function>CURRENT_TIMESTAMP</function> may not produce the desired
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effect. For the particular case of date/time types, one can work
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around this behavior by using
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<quote>DEFAULT TEXT 'now'</quote>
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instead of
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<quote>DEFAULT 'now'</quote>
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or
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<quote>DEFAULT CURRENT_TIMESTAMP</quote>.
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This forces <productname>Postgres</productname> to consider the constant a string
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type and then to convert the value to <type>timestamp</type> at runtime.
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</para>
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</refsect2>
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<refsect2 id="R2-SQL-DEFAULTCLAUSE-4">
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<title>
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Usage
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</title>
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<para>
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To assign a constant value as the default for the
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columns <literal>did</literal> and <literal>number</literal>,
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and a string literal to the column <literal>did</literal>:
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<programlisting>
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CREATE TABLE video_sales (
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did VARCHAR(40) DEFAULT 'luso films',
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number INTEGER DEFAULT 0,
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total CASH DEFAULT '$0.0'
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);
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</programlisting>
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</para>
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<para>
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To assign an existing sequence
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as the default for the column <literal>did</literal>,
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and a literal to the column <literal>name</literal>:
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<programlisting>
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CREATE TABLE distributors (
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did DECIMAL(3) DEFAULT NEXTVAL('serial'),
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name VARCHAR(40) DEFAULT 'luso films'
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);
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</programlisting>
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</para>
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</refsect2>
|
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</refsect1>
|
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|
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<refsect1 id="R1-SQL-COLUMNCONSTRAINT-1">
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<title id="R1-SQL-COLUMNCONSTRAINT-1-TITLE">
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Column CONSTRAINT Clause
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</title>
|
|
<para>
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<synopsis>
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[ CONSTRAINT <replaceable class="parameter">name</replaceable> ] { [
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NULL | NOT NULL ] | UNIQUE | PRIMARY KEY | CHECK <replaceable
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class="parameter">constraint</replaceable> | REFERENCES
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<replaceable class="parameter">reftable</replaceable>
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|
(<replaceable class="parameter">refcolumn</replaceable>)
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|
[ MATCH <replaceable class="parameter">matchtype</replaceable> ]
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|
[ ON DELETE <replaceable class="parameter">action</replaceable> ]
|
|
[ ON UPDATE <replaceable class="parameter">action</replaceable> ]
|
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[ [ NOT ] DEFERRABLE ]
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[ INITIALLY <replaceable class="parameter">checktime</replaceable> ] }
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[, ...]
|
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</synopsis>
|
|
</para>
|
|
|
|
<refsect2 id="R2-SQL-COLUMNCONSTRAINT-1">
|
|
<title>
|
|
Inputs
|
|
</title>
|
|
<para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">name</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
An arbitrary name given to the integrity constraint.
|
|
If <replaceable class="parameter">name</replaceable> is not specified,
|
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it is generated from the table and column names,
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which should ensure uniqueness for
|
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<replaceable class="parameter">name</replaceable>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
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<varlistentry>
|
|
<term>NULL</term>
|
|
<listitem>
|
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<para>
|
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The column is allowed to contain NULL values. This is the default.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
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<varlistentry>
|
|
<term>NOT NULL</term>
|
|
<listitem>
|
|
<para>
|
|
The column is not allowed to contain NULL values.
|
|
This is equivalent to the column constraint
|
|
CHECK (<replaceable class="PARAMETER">column</replaceable> NOT NULL).
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>UNIQUE</term>
|
|
<listitem>
|
|
<para>
|
|
The column must have unique values. In <productname>Postgres</productname>
|
|
this is enforced by an implicit creation of a unique index on the table.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
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<varlistentry>
|
|
<term>PRIMARY KEY</term>
|
|
<listitem>
|
|
<para>
|
|
This column is a primary key, which implies that uniqueness is
|
|
enforced by the system and that other tables may rely on this column
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|
as a unique identifier for rows.
|
|
See PRIMARY KEY for more information.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>
|
|
<replaceable class="parameter">constraint</replaceable>
|
|
</term>
|
|
<listitem>
|
|
<para>
|
|
The definition of the constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-COLUMNCONSTRAINT-2">
|
|
<title>
|
|
Description
|
|
</title>
|
|
|
|
<para>
|
|
The optional constraint
|
|
clauses specify constraints or tests which new or updated entries
|
|
must satisfy for an insert or update operation to succeed. Each constraint
|
|
must evaluate to a boolean expression. Multiple attributes may be referenced within
|
|
a single constraint. The use of PRIMARY KEY
|
|
as a table constraint
|
|
is mutually incompatible with PRIMARY KEY as a column constraint.
|
|
</para>
|
|
|
|
<para>
|
|
A constraint is a named rule: an SQL object which helps define
|
|
valid sets of values by putting limits on the results of INSERT,
|
|
UPDATE or DELETE operations performed on a Base Table.
|
|
</para>
|
|
|
|
<para>
|
|
There are two ways to define integrity constraints:
|
|
table constraints, covered later, and column constraints, covered here.
|
|
</para>
|
|
|
|
<para>
|
|
A column constraint is an integrity constraint defined as part
|
|
of a column definition, and logically becomes a table
|
|
constraint as soon as it is created. The column
|
|
constraints available are:
|
|
|
|
<simplelist columns="1">
|
|
<member>PRIMARY KEY</member>
|
|
<member>REFERENCES</member>
|
|
<member>UNIQUE</member>
|
|
<member>CHECK</member>
|
|
<member>NOT NULL</member>
|
|
</simplelist>
|
|
</para>
|
|
|
|
<note>
|
|
<para>
|
|
<productname>Postgres</productname> now
|
|
(new for v7.0) supports
|
|
REFERENCES integrity constraints.
|
|
</para>
|
|
</note>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-NOTNULL-1">
|
|
<title>
|
|
NOT NULL Constraint
|
|
</title>
|
|
<synopsis>
|
|
[ CONSTRAINT <replaceable class="parameter">name</replaceable> ] NOT NULL
|
|
</synopsis>
|
|
<para>
|
|
The NOT NULL constraint specifies a rule that a column may
|
|
contain only non-null values.
|
|
This is a column constraint only, and not allowed
|
|
as a table constraint.
|
|
</para>
|
|
|
|
<refsect3 id="R3-SQL-NOTNULL-1">
|
|
<title>
|
|
Outputs
|
|
</title>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><replaceable>status</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><computeroutput>
|
|
ERROR: ExecAppend: Fail to add null value in not null attribute "<replaceable class="parameter">column</replaceable>".
|
|
</computeroutput></term>
|
|
<listitem>
|
|
<para>
|
|
This error occurs at runtime if one tries to insert a null value
|
|
into a column which has a NOT NULL constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-NOTNULL-2">
|
|
<title>
|
|
Description
|
|
</title>
|
|
<para>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-NOTNULL-3">
|
|
<title>
|
|
Usage
|
|
</title>
|
|
|
|
<para>
|
|
Define two NOT NULL column constraints on the table
|
|
<classname>distributors</classname>,
|
|
one of which being a named constraint:
|
|
|
|
<programlisting>
|
|
CREATE TABLE distributors (
|
|
did DECIMAL(3) CONSTRAINT no_null NOT NULL,
|
|
name VARCHAR(40) NOT NULL
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
</refsect3>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-UNIQUECLAUSE-1">
|
|
<title>
|
|
UNIQUE Constraint
|
|
</title>
|
|
<synopsis>
|
|
[ CONSTRAINT <replaceable class="parameter">name</replaceable> ] UNIQUE
|
|
</synopsis>
|
|
|
|
<refsect3>
|
|
<title>Inputs</title>
|
|
<para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CONSTRAINT <replaceable class="parameter">name</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
An arbitrary label given to a constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3>
|
|
<title>Outputs</title>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><replaceable>status</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><computeroutput>
|
|
ERROR: Cannot insert a duplicate key into a unique index.
|
|
</computeroutput></term>
|
|
<listitem>
|
|
<para>
|
|
This error occurs at runtime if one tries to insert a
|
|
duplicate value into a column.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3>
|
|
<title>
|
|
Description
|
|
</title>
|
|
|
|
<para>
|
|
The UNIQUE constraint specifies a rule that a group of one or
|
|
more distinct columns of a table may contain only unique values.
|
|
</para>
|
|
<para>
|
|
The column definitions of the specified columns do not have to
|
|
include a NOT NULL constraint to be included in a UNIQUE
|
|
constraint. Having more than one null value in a column without a
|
|
NOT NULL constraint, does not violate a UNIQUE constraint.
|
|
(This deviates from the <acronym>SQL92</acronym> definition, but
|
|
is a more sensible convention. See the section on compatibility
|
|
for more details.).
|
|
</para>
|
|
<para>
|
|
Each UNIQUE column constraint must name a column that is
|
|
different from the set of columns named by any other UNIQUE or
|
|
PRIMARY KEY constraint defined for the table.
|
|
</para>
|
|
<note>
|
|
<para>
|
|
<productname>Postgres</productname> automatically creates a unique
|
|
index for each UNIQUE constraint, to assure
|
|
data integrity. See CREATE INDEX for more information.
|
|
</para>
|
|
</note>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-UNIQUECLAUSE-3">
|
|
<title>
|
|
Usage
|
|
</title>
|
|
|
|
<para>
|
|
Defines a UNIQUE column constraint for the table distributors.
|
|
UNIQUE column constraints can only be defined on one column
|
|
of the table:
|
|
<programlisting>
|
|
CREATE TABLE distributors (
|
|
did DECIMAL(3),
|
|
name VARCHAR(40) UNIQUE
|
|
);
|
|
</programlisting>
|
|
|
|
which is equivalent to the following specified as a table constraint:
|
|
<programlisting>
|
|
CREATE TABLE distributors (
|
|
did DECIMAL(3),
|
|
name VARCHAR(40),
|
|
UNIQUE(name)
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
</refsect3>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-CHECK-1">
|
|
<title>
|
|
The CHECK Constraint
|
|
</title>
|
|
<synopsis>
|
|
[ CONSTRAINT <replaceable class="parameter">name</replaceable> ] CHECK
|
|
( <replaceable>condition</replaceable> [, ...] )
|
|
</synopsis>
|
|
<refsect3 id="R3-SQL-CHECK-1">
|
|
<title>Inputs</title>
|
|
<para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">name</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
An arbitrary name given to a constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><replaceable>condition</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
Any valid conditional expression evaluating to a boolean result.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-CHECK-2">
|
|
<title>
|
|
Outputs
|
|
</title>
|
|
<para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><replaceable>status</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><computeroutput>
|
|
ERROR: ExecAppend: rejected due to CHECK constraint "<replaceable class="parameter">table_column</replaceable>".
|
|
</computeroutput></term>
|
|
<listitem>
|
|
<para>
|
|
This error occurs at runtime if one tries to insert an illegal
|
|
value into a column subject to a CHECK constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3>
|
|
<title>Description</title>
|
|
<para>
|
|
The CHECK constraint specifies a restriction on allowed values
|
|
within a column.
|
|
The CHECK constraint is also allowed as a table constraint.
|
|
</para>
|
|
<para>
|
|
The SQL92 CHECK column constraints can only be defined on, and
|
|
refer to, one column of the table. <productname>Postgres</productname>
|
|
does not have
|
|
this restriction.
|
|
</para>
|
|
</refsect3>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-PRIMARYKEY-1">
|
|
<title>
|
|
PRIMARY KEY Constraint
|
|
</title>
|
|
<synopsis>
|
|
[ CONSTRAINT <replaceable class="PARAMETER">name</replaceable> ] PRIMARY KEY
|
|
</synopsis>
|
|
|
|
<refsect3>
|
|
<title>Inputs</title>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CONSTRAINT <replaceable class="PARAMETER">name</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
An arbitrary name for the constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3>
|
|
<title>Outputs</title>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><computeroutput>
|
|
ERROR: Cannot insert a duplicate key into a unique index.
|
|
</computeroutput></term>
|
|
<listitem>
|
|
<para>
|
|
This occurs at run-time if one tries to insert a duplicate value into
|
|
a column subject to a PRIMARY KEY constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect3>
|
|
|
|
<refsect3>
|
|
<title>Description</title>
|
|
<para>
|
|
The PRIMARY KEY column constraint specifies that a column of a table
|
|
may contain only unique
|
|
(non-duplicate), non-NULL values. The definition of
|
|
the specified column does not have to include an explicit NOT NULL
|
|
constraint to be included in a PRIMARY KEY constraint.
|
|
</para>
|
|
<para>
|
|
Only one PRIMARY KEY can be specified for a table.
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-PRIMARYKEY-3">
|
|
<title>
|
|
Notes
|
|
</title>
|
|
<para>
|
|
<productname>Postgres</productname> automatically creates
|
|
a unique index to assure
|
|
data integrity. (See CREATE INDEX statement)
|
|
</para>
|
|
<para>
|
|
The PRIMARY KEY constraint should name a set of columns that is
|
|
different from other sets of columns named by any UNIQUE constraint
|
|
defined for the same table, since it will result in duplication
|
|
of equivalent indexes and unproductive additional runtime overhead.
|
|
However, <productname>Postgres</productname> does not specifically
|
|
disallow this.
|
|
</para>
|
|
</refsect3>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-REFERENCES-1">
|
|
<refsect2info>
|
|
<date>2000-02-04</date>
|
|
</refsect2info>
|
|
<title>
|
|
REFERENCES Constraint
|
|
</title>
|
|
<synopsis>
|
|
[ CONSTRAINT <replaceable class="parameter">name</replaceable> ] REFERENCES
|
|
<replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ]
|
|
[ MATCH <replaceable class="parameter">matchtype</replaceable> ]
|
|
[ ON DELETE <replaceable class="parameter">action</replaceable> ]
|
|
[ ON UPDATE <replaceable class="parameter">action</replaceable> ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
[ INITIALLY <replaceable class="parameter">checktime</replaceable> ]
|
|
</synopsis>
|
|
<para>
|
|
The REFERENCES constraint specifies a rule that a column
|
|
value is checked against the values of another column.
|
|
REFERENCES can also be specified as part of
|
|
a FOREIGN KEY table constraint.
|
|
</para>
|
|
|
|
<refsect3 id="R3-SQL-REFERENCES-1">
|
|
<title>Inputs</title>
|
|
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CONSTRAINT <replaceable class="PARAMETER">name</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
An arbitrary name for the constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">reftable</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
The table that contains the data to check against.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">refcolumn</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
The column in <replaceable class="parameter">reftable</replaceable>
|
|
to check the data against. If this is not specified, the PRIMARY KEY of the
|
|
<replaceable class="parameter">reftable</replaceable> is used.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>MATCH <replaceable class="parameter">matchtype</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
The type of comparison to do between the table data. There are three
|
|
types of matching, MATCH FULL, MATCH PARTIAL, and the unspecified match type
|
|
used if no match type is specified.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>ON DELETE <replaceable class="parameter">action</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
The action to do when a referenced row in the referenced table is being
|
|
deleted. There are the following actions.
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CASCADE</term>
|
|
<listitem>
|
|
<para>
|
|
Delete any rows referencing the deleted row.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>RESTRICT</term>
|
|
<listitem>
|
|
<para>
|
|
Disallow deletion of rows being referenced.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>SET NULL</term>
|
|
<listitem>
|
|
<para>
|
|
Set the referencing column values to NULL.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>SET DEFAULT</term>
|
|
<listitem>
|
|
<para>
|
|
Set the referencing column values to their default value.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>NO ACTION</term>
|
|
<listitem>
|
|
<para>
|
|
Do nothing.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>ON UPDATE <replaceable class="parameter">action</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
The action to do when a referenced column in the referenced table is being
|
|
updated to a new value. If the row is updated, but the referenced column
|
|
is not changed, no action is done. There are the following actions.
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CASCADE</term>
|
|
<listitem>
|
|
<para>
|
|
Update the value of the referencing column to the new value of the
|
|
referenced column.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>RESTRICT</term>
|
|
<listitem>
|
|
<para>
|
|
Disallow update of row being referenced.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>SET NULL</term>
|
|
<listitem>
|
|
<para>
|
|
Set the referencing column values to NULL.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>SET DEFAULT</term>
|
|
<listitem>
|
|
<para>
|
|
Set the referencing column values to their default value.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>NO ACTION</term>
|
|
<listitem>
|
|
<para>
|
|
Do nothing.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term> [ NOT ] DEFERRABLE </term>
|
|
<listitem>
|
|
<para>
|
|
Tells the trigger manager whether this constraint may be
|
|
deferred to the end of transaction.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>INITIALLY <replaceable class="parameter">checktime</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
<replaceable class="parameter">checktime</replaceable> has two possible values
|
|
which specify the default time to check the constraint.
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>DEFERRED</term>
|
|
<listitem>
|
|
<para>
|
|
Check this constraint at the end of the transaction.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term>IMMEDIATE</term>
|
|
<listitem>
|
|
<para>
|
|
Check this constraint after each statement.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
|
|
<refsect3 id="R3-SQL-REFERENCES-2">
|
|
<refsect3info>
|
|
<date>2000-02-04</date>
|
|
</refsect3info>
|
|
<title>
|
|
Outputs
|
|
</title>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><replaceable>status</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><computeroutput>
|
|
ERROR: <replaceable class="parameter">name</replaceable> referential integrity violation - key referenced from
|
|
<replaceable class="parameter">table</replaceable> not found in <replaceable class="parameter">reftable</replaceable>
|
|
</computeroutput></term>
|
|
<listitem>
|
|
<para>
|
|
This error occurs at runtime if one tries to insert a value
|
|
into a column which does not have a matching column in the
|
|
referenced table.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-REFERENCES-3">
|
|
<title>Description</title>
|
|
<para>
|
|
The REFERENCES column constraint specifies that a column of a
|
|
table must only contain values which match against values
|
|
in a referenced column of a referenced table.
|
|
</para>
|
|
<para>
|
|
A value added to this column are matched against the
|
|
values of the referenced table and referenced column using
|
|
the given match type.
|
|
In addition, when the referenced column data is changed,
|
|
actions are run upon this column's matching data.
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-REFERENCES-4">
|
|
<refsect3info>
|
|
<date>1998-09-11</date>
|
|
</refsect3info>
|
|
<title>
|
|
Notes
|
|
</title>
|
|
<para>
|
|
Currently <productname>Postgres</productname> only supports
|
|
MATCH FULL and an unspecified match type.
|
|
In addition, the referenced columns are supposed to be
|
|
the columns of a UNIQUE constraint in the referenced table,
|
|
however <productname>Postgres</productname> does not
|
|
enforce this.
|
|
</para>
|
|
</refsect3>
|
|
</refsect2>
|
|
</refsect1>
|
|
|
|
<refsect1 id="R1-SQL-TABLECONSTRAINT-1">
|
|
<title>
|
|
Table CONSTRAINT Clause
|
|
</title>
|
|
<para>
|
|
<synopsis>
|
|
[ CONSTRAINT name ] { PRIMARY KEY | UNIQUE } ( <replaceable class="parameter">column</replaceable> [, ...] )
|
|
[ CONSTRAINT name ] CHECK ( <replaceable>constraint</replaceable> )
|
|
[ CONSTRAINT name ] FOREIGN KEY ( <replaceable class="parameter">column</replaceable> [, ...] )
|
|
REFERENCES <replaceable class="parameter">reftable</replaceable>
|
|
(<replaceable class="parameter">refcolumn</replaceable> [, ...] )
|
|
[ MATCH <replaceable class="parameter">matchtype</replaceable> ]
|
|
[ ON DELETE <replaceable class="parameter">action</replaceable> ]
|
|
[ ON UPDATE <replaceable class="parameter">action</replaceable> ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
[ INITIALLY <replaceable class="parameter">checktime</replaceable> ]
|
|
</synopsis>
|
|
</para>
|
|
<refsect2 id="R2-SQL-TABLECONSTRAINT-1">
|
|
<title>
|
|
Inputs
|
|
</title>
|
|
|
|
<para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CONSTRAINT <replaceable class="parameter">name</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
An arbitrary name given to an integrity constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">column</replaceable> [, ...]</term>
|
|
<listitem>
|
|
<para>
|
|
The column name(s) for which to define a unique index
|
|
and, for PRIMARY KEY, a NOT NULL constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>CHECK ( <replaceable class="parameter">constraint</replaceable> )</term>
|
|
<listitem>
|
|
<para>
|
|
A boolean expression to be evaluated as the constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-TABLECONSTRAINT-2">
|
|
<title>
|
|
Outputs
|
|
</title>
|
|
|
|
<para>
|
|
The possible outputs for the table constraint clause are the same
|
|
as for the corresponding portions of the column constraint clause.
|
|
</para>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-TABLECONSTRAINT-3">
|
|
<title>
|
|
Description
|
|
</title>
|
|
|
|
<para>
|
|
A table constraint is an integrity constraint defined on one or
|
|
more columns of a base table. The four variations of "Table
|
|
Constraint" are:
|
|
<simplelist columns="1">
|
|
<member>UNIQUE</member>
|
|
<member>CHECK</member>
|
|
<member>PRIMARY KEY</member>
|
|
<member>FOREIGN KEY</member>
|
|
</simplelist>
|
|
</para>
|
|
|
|
<note>
|
|
<para>
|
|
<productname>Postgres</productname> now
|
|
supports FOREIGN KEY
|
|
integrity constraints
|
|
</para>
|
|
</note>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-UNIQUECLAUSE-4">
|
|
<title>
|
|
UNIQUE Constraint
|
|
</title>
|
|
<para>
|
|
<synopsis>
|
|
[ CONSTRAINT <replaceable class="parameter">name</replaceable> ] UNIQUE ( <replaceable class="parameter">column</replaceable> [, ...] )
|
|
</synopsis>
|
|
</para>
|
|
<refsect3>
|
|
<title>Inputs</title>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CONSTRAINT <replaceable class="parameter">name</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
An arbitrary name given to a constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">column</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
A name of a column in a table.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect3>
|
|
|
|
<refsect3>
|
|
<title>Outputs</title>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><replaceable>status</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>ERROR: Cannot insert a duplicate key into a unique index</term>
|
|
<listitem>
|
|
<para>
|
|
This error occurs at runtime if one tries to insert a
|
|
duplicate value into a column.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3>
|
|
<title>
|
|
Description
|
|
</title>
|
|
|
|
<para>
|
|
The UNIQUE constraint specifies a rule that a group of one or
|
|
more distinct columns of a table may contain only unique values.
|
|
The behavior of the UNIQUE table constraint is the same as that for column
|
|
constraints, with the additional capability to span multiple columns.
|
|
</para>
|
|
<para>
|
|
See the section on the UNIQUE column constraint for more details.
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-UNIQUECLAUSE-4">
|
|
<title>
|
|
Usage
|
|
</title>
|
|
|
|
<para>
|
|
Define a UNIQUE table constraint for the table distributors:
|
|
<programlisting>
|
|
CREATE TABLE distributors (
|
|
did DECIMAL(03),
|
|
name VARCHAR(40),
|
|
UNIQUE(name)
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
</refsect3>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-PRIMARYKEY-4">
|
|
<title>
|
|
PRIMARY KEY Constraint
|
|
</title>
|
|
<para>
|
|
<synopsis>
|
|
[ CONSTRAINT <replaceable class="PARAMETER">name</replaceable> ] PRIMARY KEY ( <replaceable class="PARAMETER">column</replaceable> [, ...] )
|
|
</synopsis>
|
|
</para>
|
|
<refsect3>
|
|
<title>Inputs</title>
|
|
<para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CONSTRAINT <replaceable class="PARAMETER">name</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
An arbitrary name for the constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><replaceable class="PARAMETER">column</replaceable> [, ...]</term>
|
|
<listitem>
|
|
<para>
|
|
The names of one or more columns in the table.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3>
|
|
<title>Outputs</title>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><replaceable>status</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>ERROR: Cannot insert a duplicate key into a unique index.</term>
|
|
<listitem>
|
|
<para>
|
|
This occurs at run-time if one tries to insert a duplicate value into
|
|
a column subject to a PRIMARY KEY constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect3>
|
|
|
|
<refsect3>
|
|
<title>Description</title>
|
|
<para>
|
|
The PRIMARY KEY constraint specifies a rule that a group of one
|
|
or more distinct columns of a table may contain only unique,
|
|
(non duplicate), non-null values. The column definitions of
|
|
the specified columns do not have to include a NOT NULL
|
|
constraint to be included in a PRIMARY KEY constraint.
|
|
</para>
|
|
|
|
<para>
|
|
The PRIMARY KEY table constraint is similar to that for column constraints,
|
|
with the additional capability of encompassing multiple columns.
|
|
</para>
|
|
<para>
|
|
Refer to the section on the PRIMARY KEY column constraint for more
|
|
information.
|
|
</para>
|
|
</refsect3>
|
|
</refsect2>
|
|
|
|
<refsect2 id="R2-SQL-REFERENCES-2">
|
|
<refsect2info>
|
|
<date>2000-02-04</date>
|
|
</refsect2info>
|
|
<title>
|
|
REFERENCES Constraint
|
|
</title>
|
|
<synopsis>
|
|
[ CONSTRAINT <replaceable class="parameter">name</replaceable> ]
|
|
FOREIGN KEY ( <replaceable class="parameter">column</replaceable> [, ...] ) REFERENCES
|
|
<replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> [, ...] ) ]
|
|
[ MATCH <replaceable class="parameter">matchtype</replaceable> ]
|
|
[ ON DELETE <replaceable class="parameter">action</replaceable> ]
|
|
[ ON UPDATE <replaceable class="parameter">action</replaceable> ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
[ INITIALLY <replaceable class="parameter">checktime</replaceable> ]
|
|
</synopsis>
|
|
<para>
|
|
The REFERENCES constraint specifies a rule that a column
|
|
value is checked against the values of another column.
|
|
REFERENCES can also be specified as part of
|
|
a FOREIGN KEY table constraint.
|
|
</para>
|
|
|
|
<refsect3 id="R3-SQL-REFERENCES-5">
|
|
<title>Inputs</title>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CONSTRAINT <replaceable class="PARAMETER">name</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
An arbitrary name for the constraint.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><replaceable class="PARAMETER">column</replaceable> [, ...]</term>
|
|
<listitem>
|
|
<para>
|
|
The names of one or more columns in the table.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">reftable</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
The table that contains the data to check against.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">referenced column</replaceable> [, ...]</term>
|
|
<listitem>
|
|
<para>
|
|
One or more column in the <replaceable class="parameter">reftable</replaceable>
|
|
to check the data against. If this is not specified, the PRIMARY KEY of the
|
|
<replaceable class="parameter">reftable</replaceable> is used.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>MATCH <replaceable class="parameter">matchtype</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
The type of comparison to do between the table data. There are three
|
|
types of matching, MATCH FULL, MATCH PARTIAL, and the unspecified match type
|
|
used if no match type is specified.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>ON DELETE <replaceable class="parameter">action</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
The action to do when a referenced row in the referenced table is being
|
|
deleted. There are the following actions.
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CASCADE</term>
|
|
<listitem>
|
|
<para>
|
|
Delete any rows referencing the deleted row.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>RESTRICT</term>
|
|
<listitem>
|
|
<para>
|
|
Disallow deletion of rows being referenced.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>SET NULL</term>
|
|
<listitem>
|
|
<para>
|
|
Set the referencing column values to NULL.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>SET DEFAULT</term>
|
|
<listitem>
|
|
<para>
|
|
Set the referencing column values to their default value.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>NO ACTION</term>
|
|
<listitem>
|
|
<para>
|
|
Do nothing.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>ON UPDATE <replaceable class="parameter">action</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
The action to do when a referenced column in the referenced table is being
|
|
updated to a new value. If the row is updated, but the referenced column
|
|
is not changed, no action is done. There are the following actions.
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>CASCADE</term>
|
|
<listitem>
|
|
<para>
|
|
Update the value of the referencing column to the new value of the
|
|
referenced column.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>RESTRICT</term>
|
|
<listitem>
|
|
<para>
|
|
Disallow update of row being referenced.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>SET NULL</term>
|
|
<listitem>
|
|
<para>
|
|
Set the referencing column values to NULL.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>SET DEFAULT</term>
|
|
<listitem>
|
|
<para>
|
|
Set the referencing column values to their default value.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>NO ACTION</term>
|
|
<listitem>
|
|
<para>
|
|
Do nothing.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term> [ NOT ] DEFERRABLE </term>
|
|
<listitem>
|
|
<para>
|
|
Tells the trigger manager whether this constraint may be
|
|
deferred to the end of transaction.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>INITIALLY <replaceable class="parameter">checktime</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
<replaceable class="parameter">checktime</replaceable> has two possible values
|
|
which specify the default time to check the constraint.
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>DEFERRED</term>
|
|
<listitem>
|
|
<para>
|
|
Check this constraint at the end of the transaction.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>IMMEDIATE</term>
|
|
<listitem>
|
|
<para>
|
|
Check this constraint after each statement.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
<refsect3 id="R3-SQL-REFERENCES-6">
|
|
<refsect3info>
|
|
<date>2000-02-04</date>
|
|
</refsect3info>
|
|
<title>
|
|
Outputs
|
|
</title>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><replaceable>status</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><computeroutput>
|
|
ERROR: <replaceable class="parameter">name</replaceable> referential integrity violation - key referenced from
|
|
<replaceable class="parameter">table</replaceable> not found in <replaceable class="parameter">reftable</replaceable>
|
|
</computeroutput></term>
|
|
<listitem>
|
|
<para>
|
|
This error occurs at runtime if one tries to insert a value
|
|
into a column which does not have a matching column in the
|
|
referenced table.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
<refsect3>
|
|
<title>Description</title>
|
|
<para>
|
|
The FOREIGN KEY constraint specifies a rule that a group of one
|
|
or more distinct columns of a table are related to a group
|
|
of distinct columns in the referenced table.
|
|
</para>
|
|
|
|
<para>
|
|
The FOREIGN KEY table constraint is similar to that for column constraints,
|
|
with the additional capability of encompassing multiple columns.
|
|
</para>
|
|
<para>
|
|
Refer to the section on the FOREIGN KEY column constraint for more
|
|
information.
|
|
</para>
|
|
</refsect3>
|
|
|
|
</refsect2>
|
|
|
|
</refsect1>
|
|
|
|
<refsect1 id="R1-SQL-CREATETABLE-2">
|
|
<title>
|
|
Usage
|
|
</title>
|
|
<para>
|
|
Create table films and table distributors:
|
|
|
|
<programlisting>
|
|
CREATE TABLE films (
|
|
code CHARACTER(5) CONSTRAINT firstkey PRIMARY KEY,
|
|
title CHARACTER VARYING(40) NOT NULL,
|
|
did DECIMAL(3) NOT NULL,
|
|
date_prod DATE,
|
|
kind CHAR(10),
|
|
len INTERVAL HOUR TO MINUTE
|
|
);
|
|
</programlisting>
|
|
|
|
<programlisting>
|
|
CREATE TABLE distributors (
|
|
did DECIMAL(03) PRIMARY KEY DEFAULT NEXTVAL('serial'),
|
|
name VARCHAR(40) NOT NULL CHECK (name <> '')
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Create a table with a 2-dimensional array:
|
|
|
|
<programlisting>
|
|
CREATE TABLE array (
|
|
vector INT[][]
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Define a UNIQUE table constraint for the table films.
|
|
UNIQUE table constraints can be defined on one or more
|
|
columns of the table:
|
|
|
|
<programlisting>
|
|
CREATE TABLE films (
|
|
code CHAR(5),
|
|
title VARCHAR(40),
|
|
did DECIMAL(03),
|
|
date_prod DATE,
|
|
kind CHAR(10),
|
|
len INTERVAL HOUR TO MINUTE,
|
|
CONSTRAINT production UNIQUE(date_prod)
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Define a CHECK column constraint:
|
|
|
|
<programlisting>
|
|
CREATE TABLE distributors (
|
|
did DECIMAL(3) CHECK (did > 100),
|
|
name VARCHAR(40)
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Define a CHECK table constraint:
|
|
|
|
<programlisting>
|
|
CREATE TABLE distributors (
|
|
did DECIMAL(3),
|
|
name VARCHAR(40)
|
|
CONSTRAINT con1 CHECK (did > 100 AND name > '')
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Define a PRIMARY KEY table constraint for the table films.
|
|
PRIMARY KEY table constraints can be defined on one or more
|
|
columns of the table:
|
|
|
|
<programlisting>
|
|
CREATE TABLE films (
|
|
code CHAR(05),
|
|
title VARCHAR(40),
|
|
did DECIMAL(03),
|
|
date_prod DATE,
|
|
kind CHAR(10),
|
|
len INTERVAL HOUR TO MINUTE,
|
|
CONSTRAINT code_title PRIMARY KEY(code,title)
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Defines a PRIMARY KEY column constraint for table distributors.
|
|
PRIMARY KEY column constraints can only be defined on one column
|
|
of the table (the following two examples are equivalent):
|
|
|
|
<programlisting>
|
|
CREATE TABLE distributors (
|
|
did DECIMAL(03),
|
|
name CHAR VARYING(40),
|
|
PRIMARY KEY(did)
|
|
);
|
|
</programlisting>
|
|
|
|
<programlisting>
|
|
CREATE TABLE distributors (
|
|
did DECIMAL(03) PRIMARY KEY,
|
|
name VARCHAR(40)
|
|
);
|
|
</programlisting>
|
|
</para>
|
|
|
|
<refsect2 id="R2-SQL-CREATETABLE-3">
|
|
<title>
|
|
Notes
|
|
</title>
|
|
<para>
|
|
CREATE TABLE/INHERITS is a <productname>Postgres</productname>
|
|
language extension.
|
|
</para>
|
|
</refsect2>
|
|
|
|
</refsect1>
|
|
|
|
<refsect1 id="R1-SQL-CREATETABLE-3">
|
|
<title>
|
|
Compatibility
|
|
</title>
|
|
|
|
<refsect2 id="R2-SQL-CREATETABLE-4">
|
|
<title>
|
|
SQL92
|
|
</title>
|
|
<para>
|
|
In addition to the locally-visible temporary table, SQL92 also defines a
|
|
CREATE GLOBAL TEMPORARY TABLE statement, and optionally an
|
|
ON COMMIT clause:
|
|
<synopsis>
|
|
CREATE GLOBAL TEMPORARY TABLE <replaceable class="parameter">table</replaceable> ( <replaceable class="parameter">column</replaceable> <replaceable class="parameter">type</replaceable> [
|
|
DEFAULT <replaceable class="parameter">value</replaceable> ] [ CONSTRAINT <replaceable class="parameter">column_constraint</replaceable> ] [, ...] )
|
|
[ CONSTRAINT <replaceable class="parameter">table_constraint</replaceable> ] [ ON COMMIT { DELETE | PRESERVE } ROWS ]
|
|
</synopsis>
|
|
</para>
|
|
|
|
<para>
|
|
For temporary tables, the CREATE GLOBAL TEMPORARY TABLE statement
|
|
names a new table visible to other clients and defines the table's columns and
|
|
constraints.
|
|
</para>
|
|
<para>
|
|
The optional ON COMMIT clause of CREATE TEMPORARY TABLE
|
|
specifies whether or not the temporary table should be emptied of
|
|
rows whenever COMMIT is executed. If the ON COMMIT clause is
|
|
omitted, the default option, ON COMMIT DELETE ROWS, is assumed.
|
|
</para>
|
|
<para>
|
|
To create a temporary table:
|
|
|
|
<programlisting>
|
|
CREATE TEMPORARY TABLE actors (
|
|
id DECIMAL(03),
|
|
name VARCHAR(40),
|
|
CONSTRAINT actor_id CHECK (id < 150)
|
|
) ON COMMIT DELETE ROWS;
|
|
</programlisting>
|
|
</para>
|
|
|
|
<refsect3 id="R3-SQL-UNIQUECLAUSE-1">
|
|
<title>
|
|
UNIQUE clause
|
|
</title>
|
|
<para>
|
|
SQL92 specifies some additional capabilities for UNIQUE:
|
|
</para>
|
|
<para>
|
|
Table Constraint definition:
|
|
|
|
<synopsis>
|
|
[ CONSTRAINT name ] UNIQUE ( column [, ...] )
|
|
[ { INITIALLY DEFERRED | INITIALLY IMMEDIATE } ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
|
|
<para>
|
|
Column Constraint definition:
|
|
|
|
<synopsis>
|
|
[ CONSTRAINT name ] UNIQUE
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-NULL-1">
|
|
<title>
|
|
NULL clause
|
|
</title>
|
|
<para>
|
|
The NULL "constraint" (actually a non-constraint)
|
|
is a <productname>Postgres</productname> extension to SQL92
|
|
is included for symmetry with the NOT NULL clause. Since it is the default
|
|
for any column, its presence is simply noise.
|
|
<synopsis>
|
|
[ CONSTRAINT name ] NULL
|
|
</synopsis>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-NOTNULL-4">
|
|
<title>
|
|
NOT NULL clause
|
|
</title>
|
|
<para>
|
|
|
|
SQL92 specifies some additional capabilities for NOT NULL:
|
|
<synopsis>
|
|
[ CONSTRAINT name ] NOT NULL
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
</refsect3>
|
|
|
|
<!--
|
|
I can't figure out why DEFAULT clause is different from what we already have.
|
|
Perhaps because CURRENT_USER and CURRENT_DATE have specific types (currently
|
|
the "name" type), if you aren't careful then the types won't match up with
|
|
the column. Not our problem...
|
|
- Thomas 1998-08-16
|
|
|
|
<REFSECT3 ID="R3-SQL-DEFAULTCLAUSE-1">
|
|
<TITLE>
|
|
DEFAULT clause
|
|
</TITLE>
|
|
<PARA>
|
|
SQL92 specifies some additional capabilities for the DEFAULT clause.
|
|
A DEFAULT clause is used to set the default value for a column
|
|
or a domain.
|
|
</para>
|
|
<synopsis>
|
|
DEFAULT niladic USER function |
|
|
niladic datetime function |
|
|
NULL
|
|
</synopsis>
|
|
</refsect3>
|
|
-->
|
|
|
|
<refsect3 id="R3-SQL-CONSTRAINT-3">
|
|
<title>
|
|
CONSTRAINT clause
|
|
</title>
|
|
<para>
|
|
SQL92 specifies some additional capabilities for constraints,
|
|
and also defines assertions and domain constraints.
|
|
<note>
|
|
<para>
|
|
<productname>Postgres</productname> does not yet support
|
|
either domains or assertions.
|
|
</para>
|
|
</note>
|
|
</para>
|
|
<para>
|
|
An assertion is a special type of integrity constraint and share
|
|
the same namespace as other constraints.
|
|
However, an assertion is not necessarily dependent on one
|
|
particular base table as constraints are, so SQL-92 provides the
|
|
CREATE ASSERTION statement as an alternate method for defining a
|
|
constraint:
|
|
</para>
|
|
<synopsis>
|
|
CREATE ASSERTION name CHECK ( condition )
|
|
</synopsis>
|
|
|
|
<para>
|
|
Domain constraints are defined by CREATE DOMAIN or ALTER DOMAIN
|
|
statements:
|
|
</para>
|
|
<para>
|
|
Domain constraint:
|
|
|
|
<synopsis>
|
|
[ CONSTRAINT name ] CHECK constraint
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
|
|
<para>
|
|
Table constraint definition:
|
|
|
|
<synopsis>
|
|
[ CONSTRAINT name ] { PRIMARY KEY ( <replaceable class="parameter">column</replaceable>, ... ) | FOREIGN KEY constraint | UNIQUE constraint | CHECK constraint }
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
|
|
<para>
|
|
Column constraint definition:
|
|
|
|
<synopsis>
|
|
[ CONSTRAINT name ] { NOT NULL | PRIMARY KEY | FOREIGN KEY constraint | UNIQUE | CHECK constraint }
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
|
|
<para>
|
|
A CONSTRAINT definition may contain one deferment attribute
|
|
clause and/or one initial constraint mode clause, in any order.
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>NOT DEFERRABLE</term>
|
|
<listitem>
|
|
<para>
|
|
means that the Constraint must be checked for
|
|
violation of its rule after the execution of every SQL statement.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>DEFERRABLE</term>
|
|
<listitem>
|
|
<para>
|
|
means that checking of the Constraint may be deferred
|
|
until some later time, but no later than the end of the current
|
|
transaction.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
<para>
|
|
The constraint mode for every Constraint always has an initial
|
|
default value which is set for that Constraint at the beginning
|
|
of a transaction.
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term>INITIALLY IMMEDIATE</term>
|
|
<listitem>
|
|
<para>
|
|
means that, as of the start of the transaction,
|
|
the Constraint must be checked for violation of its rule after the
|
|
execution of every SQL statement.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term>INITIALLY DEFERRED</term>
|
|
<listitem>
|
|
<para>
|
|
means that, as of the start of the transaction,
|
|
checking of the Constraint may be deferred until some later time,
|
|
but no later than the end of the current transaction.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</refsect3>
|
|
|
|
|
|
<refsect3 id="R3-SQL-CHECK-4">
|
|
<title>
|
|
CHECK clause
|
|
</title>
|
|
<para>
|
|
SQL92 specifies some additional capabilities for CHECK in either
|
|
table or column constraints.
|
|
</para>
|
|
<!--
|
|
Constraints associated with domains do not need to be mentioned here,
|
|
even though it is the case that a domain constraint may possibly
|
|
affect a column or a table.
|
|
- Thomas 1998-08-16
|
|
<para>
|
|
A CHECK constraint is either a table constraint, a column
|
|
constraint or a domain constraint.
|
|
</para>
|
|
-->
|
|
<para>
|
|
table constraint definition:
|
|
<synopsis>
|
|
[ CONSTRAINT name ] CHECK ( VALUE condition )
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
|
|
<para>
|
|
column constraint definition:
|
|
<synopsis>
|
|
[ CONSTRAINT name ] CHECK ( VALUE condition )
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
<!--
|
|
<para>
|
|
domain constraint definition:
|
|
</para>
|
|
<synopsis>
|
|
[ CONSTRAINT name ]
|
|
CHECK ( VALUE condition )
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
<para>
|
|
CHECK domain constraints can be defined in either
|
|
a CREATE DOMAIN statement or an ALTER DOMAIN statement:
|
|
</para>
|
|
<programlisting>
|
|
CREATE DOMAIN duration AS SMALLINT
|
|
CONSTRAINT minutes CHECK (VALUE IN (90,120,180,240));
|
|
|
|
ALTER DOMAIN cities
|
|
ADD CONSTRAINT new_city CHECK (VALUE LIKE 'L%');
|
|
</programlisting>
|
|
-->
|
|
</refsect3>
|
|
|
|
<refsect3 id="R3-SQL-PRIMARYKEY-1">
|
|
<title>
|
|
PRIMARY KEY clause
|
|
</title>
|
|
<para>
|
|
SQL92 specifies some additional capabilities for PRIMARY KEY:
|
|
</para>
|
|
<para>
|
|
Table Constraint definition:
|
|
<synopsis>
|
|
[ CONSTRAINT name ] PRIMARY KEY ( column [, ...] )
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
<para>
|
|
Column Constraint definition:
|
|
<synopsis>
|
|
[ CONSTRAINT name ] PRIMARY KEY
|
|
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
|
|
[ [ NOT ] DEFERRABLE ]
|
|
</synopsis>
|
|
</para>
|
|
</refsect3>
|
|
</refsect2>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<!-- Keep this comment at the end of the file
|
|
Local variables:
|
|
mode: sgml
|
|
sgml-omittag:nil
|
|
sgml-shorttag:t
|
|
sgml-minimize-attributes:nil
|
|
sgml-always-quote-attributes:t
|
|
sgml-indent-step:1
|
|
sgml-indent-data:t
|
|
sgml-parent-document:nil
|
|
sgml-default-dtd-file:"../reference.ced"
|
|
sgml-exposed-tags:nil
|
|
sgml-local-catalogs:"/usr/lib/sgml/catalog"
|
|
sgml-local-ecat-files:nil
|
|
End:
|
|
-->
|