Minor copy-editing.
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<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ddl.sgml,v 1.22 2003/11/04 09:55:38 petere Exp $ -->
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<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ddl.sgml,v 1.23 2003/11/05 00:05:32 tgl Exp $ -->
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<chapter id="ddl">
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<title>Data Definition</title>
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@ -12,8 +12,7 @@
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Subsequently, we discuss how tables can be organized into
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schemas, and how privileges can be assigned to tables. Finally,
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we will briefly look at other features that affect the data storage,
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such as views, functions, and triggers. Detailed information on
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these topics is found in <xref linkend="server-programming">.
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such as views, functions, and triggers.
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</para>
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<sect1 id="ddl-basics">
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@ -522,7 +521,7 @@ CREATE TABLE products (
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<para>
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It should be noted that a check constraint is satisfied if the
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check expression evaluates to true or the null value. Since most
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expressions will evaluate to the null value if one operand is null
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expressions will evaluate to the null value if one operand is null,
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they will not prevent null values in the constrained columns. To
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ensure that a column does not contain null values, the not-null
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constraint described in the next section should be used.
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@ -586,7 +585,7 @@ CREATE TABLE products (
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The <literal>NULL</literal> constraint is not defined in the SQL
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standard and should not be used in portable applications. (It was
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only added to <productname>PostgreSQL</productname> to be
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compatible with other database systems.) Some users, however,
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compatible with some other database systems.) Some users, however,
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like it because it makes it easy to toggle the constraint in a
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script file. For example, you could start with
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<programlisting>
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@ -820,7 +819,7 @@ CREATE TABLE orders (
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);
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</programlisting>
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because in absence of a column list the primary key of the
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referenced table is used as referenced column.
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referenced table is used as the referenced column.
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</para>
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<para>
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@ -1094,9 +1093,10 @@ WHERE c.altitude > 500 and c.tableoid = p.oid;
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<title>Deprecated</title>
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<para>
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In previous versions of <productname>PostgreSQL</productname>, the
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default was not to get access to child tables. This was found to
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be error prone and is also in violation of the SQL99 standard. Under the old
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syntax, to get the sub-tables you append <literal>*</literal> to the table name.
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default behavior was not to include child tables in queries. This was
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found to be error prone and is also in violation of the SQL99
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standard. Under the old syntax, to get the sub-tables you append
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<literal>*</literal> to the table name.
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For example
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<programlisting>
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SELECT * from cities*;
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@ -1270,6 +1270,12 @@ ALTER TABLE products ALTER COLUMN product_no SET NOT NULL;
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<programlisting>
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ALTER TABLE products DROP CONSTRAINT some_name;
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</programlisting>
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(If you are dealing with a generated constraint name like <literal>$2</>,
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don't forget that you'll need to double-quote it to make it a valid
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identifier.)
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</para>
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<para>
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This works the same for all constraint types except not-null
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constraints. To drop a not null constraint use
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<programlisting>
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@ -1739,9 +1745,11 @@ SELECT 3 OPERATOR(pg_catalog.+) 4;
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A user can also be allowed to create objects in someone else's
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schema. To allow that, the <literal>CREATE</literal> privilege on
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the schema needs to be granted. Note that by default, everyone
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has the <literal>CREATE</literal> privilege on the schema
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<literal>public</literal>. This allows all users that manage to
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connect to a given database to create objects there. If you do
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has <literal>CREATE</literal> and <literal>USAGE</literal> privileges on
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the schema
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<literal>public</literal>. This allows all users that are able to
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connect to a given database to create objects in its
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<literal>public</literal> schema. If you do
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not want to allow that, you can revoke that privilege:
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<programlisting>
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REVOKE CREATE ON SCHEMA public FROM PUBLIC;
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@ -1905,6 +1913,11 @@ REVOKE CREATE ON SCHEMA public FROM PUBLIC;
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</para>
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</listitem>
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</itemizedlist>
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<para>
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Detailed information on
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these topics appears in <xref linkend="server-programming">.
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</para>
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</sect1>
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<sect1 id="ddl-depend">
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