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Some desultory copy-editing.

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Tom Lane 2006-10-22 03:03:41 +00:00
parent ed19393326
commit fa5d08fbf8
3 changed files with 46 additions and 39 deletions
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71
doc/src/sgml/ddl.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.65 2006/10/16 17:28:03 momjian Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.66 2006/10/22 03:03:40 tgl Exp $ -->
<chapter id="ddl">
<title>Data Definition</title>
@ -146,8 +146,10 @@ DROP TABLE products;
</programlisting>
Attempting to drop a table that does not exist is an error.
Nevertheless, it is common in SQL script files to unconditionally
try to drop each table before creating it, ignoring the error
messages.
try to drop each table before creating it, ignoring any error
messages, so that the script works whether or not the table exists.
(If you like, you can use the <literal>DROP TABLE IF EXISTS</> variant
to avoid the error messages, but this is not standard SQL.)
</para>
<para>
@ -174,7 +176,7 @@ DROP TABLE products;
<para>
A column can be assigned a default value. When a new row is
created and no values are specified for some of the columns, the
created and no values are specified for some of the columns, those
columns will be filled with their respective default values. A
data manipulation command can also request explicitly that a column
be set to its default value, without having to know what that value is.
@ -245,7 +247,7 @@ CREATE TABLE products (
standard data type that accepts only positive numbers. Another issue is
that you might want to constrain column data with respect to other
columns or rows. For example, in a table containing product
information, there should only be one row for each product number.
information, there should be only one row for each product number.
</para>
<para>
@ -400,11 +402,6 @@ CREATE TABLE products (
ensure that a column does not contain null values, the not-null
constraint described in the next section can be used.
</para>
<para>
Check constraints can be useful for enhancing the performance of
partitioned tables. For details see <xref linkend="ddl-partitioning">.
</para>
</sect2>
<sect2>
@ -461,7 +458,7 @@ CREATE TABLE products (
<literal>NULL</literal> constraint. This does not mean that the
column must be null, which would surely be useless. Instead, this
simply selects the default behavior that the column may be null.
The <literal>NULL</literal> constraint is not defined in the SQL
The <literal>NULL</literal> constraint is not present in the SQL
standard and should not be used in portable applications. (It was
only added to <productname>PostgreSQL</productname> to be
compatible with some other database systems.) Some users, however,
@ -556,7 +553,7 @@ CREATE TABLE products (
In general, a unique constraint is violated when there are two or
more rows in the table where the values of all of the
columns included in the constraint are equal.
However, null values are not considered equal in this
However, two null values are not considered equal in this
comparison. That means even in the presence of a
unique constraint it is possible to store duplicate
rows that contain a null value in at least one of the constrained
@ -626,8 +623,10 @@ CREATE TABLE example (
</para>
<para>
A table can have at most one primary key (while it can have many
unique and not-null constraints). Relational database theory
A table can have at most one primary key. (There can be any number
of unique and not-null constraints, which are functionally the same
thing, but only one can be identified as the primary key.)
Relational database theory
dictates that every table must have a primary key. This rule is
not enforced by <productname>PostgreSQL</productname>, but it is
usually best to follow it.
@ -878,7 +877,7 @@ CREATE TABLE order_items (
The object identifier (object ID) of a row. This column is only
present if the table was created using <literal>WITH
OIDS</literal>, or if the <xref linkend="guc-default-with-oids">
configuration variable was set. This column is of type
configuration variable was set at the time. This column is of type
<type>oid</type> (same name as the column); see <xref
linkend="datatype-oid"> for more information about the type.
</para>
@ -1017,7 +1016,7 @@ CREATE TABLE order_items (
</listitem>
<listitem>
<para>
The tables in question should be created using <literal>WITH
Of course, the tables in question must be created <literal>WITH
OIDS</literal>. As of <productname>PostgreSQL</productname> 8.1,
<literal>WITHOUT OIDS</> is the default.
</para>
@ -1096,7 +1095,7 @@ CREATE TABLE order_items (
All these actions are performed using the
<xref linkend="sql-altertable" endterm="sql-altertable-title">
command.
command, which see for details beyond those given here.
</para>
<sect2>
@ -1129,6 +1128,18 @@ ALTER TABLE products ADD COLUMN description text CHECK (description &lt;&gt; '')
constraints later (see below) after you've filled in the new column
correctly.
</para>
<tip>
<para>
Adding a column with a default requires updating each row of the
table (to store the new column value). However, if no default is
specified, <productname>PostgreSQL</productname> is able to avoid
the physical update. So if you intend to fill the column with
mostly nondefault values, it's best to add the column with no default,
insert the correct values using <command>UPDATE</>, and then add any
desired default as described below.
</para>
</tip>
</sect2>
<sect2>
@ -1376,16 +1387,18 @@ ALTER TABLE products RENAME TO items;
<programlisting>
GRANT UPDATE ON accounts TO joe;
</programlisting>
To grant a privilege to a group, use this syntax:
<programlisting>
GRANT SELECT ON accounts TO GROUP staff;
</programlisting>
The special <quote>user</quote> name <literal>PUBLIC</literal> can
be used to grant a privilege to every user on the system. Writing
<literal>ALL</literal> in place of a specific privilege grants all
Writing <literal>ALL</literal> in place of a specific privilege grants all
privileges that are relevant for the object type.
</para>
<para>
The special <quote>user</quote> name <literal>PUBLIC</literal> can
be used to grant a privilege to every user on the system. Also,
<quote>group</> roles can be set up to help manage privileges when
there are many users of a database &mdash; for details see
<xref linkend="user-manag">.
</para>
<para>
To revoke a privilege, use the fittingly named
<command>REVOKE</command> command:
@ -1890,7 +1903,7 @@ REVOKE CREATE ON SCHEMA public FROM PUBLIC;
</indexterm>
<para>
<productname>PostgreSQL</productname> implements table inheritance
<productname>PostgreSQL</productname> implements table inheritance,
which can be a useful tool for database designers. (SQL:1999 and
later define a type inheritance feature, which differs in many
respects from the features described here.)
@ -2064,11 +2077,7 @@ VALUES ('New York', NULL, NULL, 'NY');
Table inheritance is typically established when the child table is
created, using the <literal>INHERITS</> clause of the
<xref linkend="sql-createtable" endterm="sql-createtable-title">
statement. However the related statement <command>CREATE TABLE AS</command>
does not allow inheritance to be specified.
</para>
<para>
statement.
Alternatively, a table which is already defined in a compatible way can
have a new parent relationship added, using the <literal>INHERIT</literal>
variant of <xref linkend="sql-altertable" endterm="sql-altertable-title">.
@ -2294,8 +2303,6 @@ VALUES ('New York', NULL, NULL, 'NY');
</listitem>
</varlistentry>
</variablelist>
Hash partitioning is not currently supported.
</para>
</sect2>

6
doc/src/sgml/queries.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/queries.sgml,v 1.36 2006/09/18 19:54:01 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/queries.sgml,v 1.37 2006/10/22 03:03:41 tgl Exp $ -->
<chapter id="queries">
<title>Queries</title>
@ -131,9 +131,9 @@ FROM <replaceable>table_reference</replaceable> <optional>, <replaceable>table_r
</indexterm>
<para>
When a table reference names a table that is the supertable of a
When a table reference names a table that is the parent of a
table inheritance hierarchy, the table reference produces rows of
not only that table but all of its subtable successors, unless the
not only that table but all of its descendant tables, unless the
key word <literal>ONLY</> precedes the table name. However, the
reference produces only the columns that appear in the named table
&mdash; any columns added in subtables are ignored.

8
doc/src/sgml/syntax.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.110 2006/10/21 17:12:07 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.111 2006/10/22 03:03:41 tgl Exp $ -->
<chapter id="sql-syntax">
<title>SQL Syntax</title>
@ -182,8 +182,8 @@ UPDATE "my_table" SET "a" = 5;
</para>
<para>
Quoted identifiers can contain any character other than a double
quote itself. (To include a double quote, write two double quotes.)
Quoted identifiers can contain any character, except the character
with code zero. (To include a double quote, write two double quotes.)
This allows constructing table or column names that would
otherwise not be possible, such as ones containing spaces or
ampersands. The length limitation still applies.
@ -251,7 +251,7 @@ UPDATE "my_table" SET "a" = 5;
<para>
Two string constants that are only separated by whitespace
<emphasis>with at least one newline</emphasis> are concatenated
and effectively treated as if the string had been written in one
and effectively treated as if the string had been written as one
constant. For example:
<programlisting>
SELECT 'foo'