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提交 40dc76e3 编写于 作者: T Tom Lane
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Recommend CREATE TABLE AS in preference to SELECT INTO. Remove the 

(inadequate anyway) mention of SELECT INTO from the main SELECT ref page.
Point out that SELECT INTO means something else in plpgsql and ecpg.
上级 192d7245
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Showing with 113 addition and 62 deletion
doc/src/sgml/ref/create_table_as.sgml
浏览文件 @ 40dc76e3
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table_as.sgml,v 1.5 2001/03/03 22:11:40 tgl Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table_as.sgml,v 1.6 2001/03/20 20:54:41 tgl Exp $
Postgres documentation
-->
......@@ -15,7 +15,7 @@ Postgres documentation
CREATE TABLE AS
</refname>
<refpurpose>
Creates a new table
Creates a new table from the results of a SELECT
</refpurpose>
</refnamediv>
<refsynopsisdiv>
......@@ -41,7 +41,7 @@ CREATE [ TEMPORARY | TEMP ] TABLE <replaceable>table</replaceable> [ (<replaceab
<term>TEMPORARY or TEMP</term>
<listitem>
<para>
If specified, the table is created only for this session, and is
If specified, the table is created only within this session, and is
automatically dropped on session exit.
Existing permanent tables with the same name are not visible
(in this session) while the temporary table exists.
......@@ -55,7 +55,10 @@ CREATE [ TEMPORARY | TEMP ] TABLE <replaceable>table</replaceable> [ (<replaceab
<term><replaceable>table</replaceable></term>
<listitem>
<para>
The name of a new table to be created.
The name of the new table to be created.
This table must not already exist. However, a temporary table
can be created that has the same name as an existing permanent
table.
</para>
</listitem>
</varlistentry>
......@@ -76,8 +79,9 @@ CREATE [ TEMPORARY | TEMP ] TABLE <replaceable>table</replaceable> [ (<replaceab
<term><replaceable>select_clause</replaceable></term>
<listitem>
<para>
A valid query statement. Refer to SELECT for a description of the
allowed syntax.
A valid query statement. Refer to
<xref linkend="sql-select" endterm="sql-select-title">
for a description of the allowed syntax.
</para>
</listitem>
</varlistentry>
......@@ -92,27 +96,47 @@ CREATE [ TEMPORARY | TEMP ] TABLE <replaceable>table</replaceable> [ (<replaceab
<title>
Outputs
</title>
<para>
Refer to <command>CREATE TABLE</command>
and <command>SELECT</command> for a summary of possible output
messages.
Refer to
<xref linkend="sql-createtable" endterm="sql-createtable-title">
and
<xref linkend="sql-select" endterm="sql-select-title">
for a summary of possible output messages.
</para>
</refsect2>
</refsynopsisdiv>
<refsect1>
<refsect1info>
<date>1998-09-22</date>
<date>2001-03-20</date>
</refsect1info>
<title>
Description
</title>
<para>
<command>CREATE TABLE AS</command> enables a table to be created
from the contents of an existing table.
It is functionally equivalent to
<command>CREATE TABLE AS</command> creates a table and fills it
with data computed by a <command>SELECT</command> command. The
table columns have the names and datatypes associated with the
output columns of the <command>SELECT</command> (except that you
can override the <command>SELECT</command> column names by giving
an explicit list of column names).
</para>
<para>
<command>CREATE TABLE AS</command> bears some resemblance to creating
a view, but it is really quite different: it creates a new table and
evaluates the <command>SELECT</command> just once to fill the new table
initially. The new table will not track subsequent changes to
the source tables of the <command>SELECT</command>. In contrast,
a view re-evaluates the given <command>SELECT</command> whenever queried.
</para>
<para>
This command is functionally equivalent to
<xref linkend="sql-selectinto" endterm="sql-selectinto-title">,
but with perhaps a more direct syntax.
but it is preferred since it is less likely to be confused with
other uses of the <command>SELECT ... INTO</command> syntax.
</para>
</refsect1>
</refentry>
......
doc/src/sgml/ref/select.sgml
浏览文件 @ 40dc76e3
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/select.sgml,v 1.38 2001/02/04 12:18:08 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/select.sgml,v 1.39 2001/03/20 20:54:41 tgl Exp $
Postgres documentation
-->
......@@ -15,7 +15,7 @@ Postgres documentation
SELECT
</refname>
<refpurpose>
Retrieve rows from a table or view.
Retrieves rows from a table or view
</refpurpose></refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
......@@ -24,7 +24,6 @@ Postgres documentation
<synopsis>
SELECT [ ALL | DISTINCT [ ON ( <replaceable class="PARAMETER">expression</replaceable> [, ...] ) ] ]
* | <replaceable class="PARAMETER">expression</replaceable> [ AS <replaceable class="PARAMETER">output_name</replaceable> ] [, ...]
[ INTO [ TEMPORARY | TEMP ] [ TABLE ] <replaceable class="PARAMETER">new_table</replaceable> ]
[ FROM <replaceable class="PARAMETER">from_item</replaceable> [, ...] ]
[ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
[ GROUP BY <replaceable class="PARAMETER">expression</replaceable> [, ...] ]
......@@ -80,39 +79,6 @@ where <replaceable class="PARAMETER">from_item</replaceable> can be:
</listitem>
</varlistentry>
<varlistentry>
<term>TEMPORARY</term>
<term>TEMP</term>
<listitem>
<para>
If TEMPORARY or TEMP is specified,
the output table is created unique to this session, and is
automatically dropped on session exit.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">new_table</replaceable></term>
<listitem>
<para>
If the INTO TABLE clause is specified, the result of the
query will be stored in a new table with the indicated
name, rather than being returned to the client.
The target table (<replaceable class="PARAMETER">new_table</replaceable>) will
be created automatically and must not exist before this command.
Refer to <command>SELECT INTO</command> for more information.
<note>
<para>
The <command>CREATE TABLE AS</command> statement will also
create a new table from a SELECT query.
</para>
</note>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">from_item</replaceable></term>
<listitem>
......
doc/src/sgml/ref/select_into.sgml
浏览文件 @ 40dc76e3
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/select_into.sgml,v 1.9 2001/01/13 23:58:55 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/select_into.sgml,v 1.10 2001/03/20 20:54:41 tgl Exp $
Postgres documentation
-->
......@@ -15,7 +15,7 @@ Postgres documentation
SELECT INTO
</refname>
<refpurpose>
Create a new table from an existing table or view
Creates a new table from the results of a SELECT
</refpurpose></refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
......@@ -48,51 +48,112 @@ where <replaceable class="PARAMETER">from_item</replaceable> can be:
<refsect2 id="R2-SQL-SELECTINTO-1">
<refsect2info>
<date>1998-09-22</date>
<date>2001-03-20</date>
</refsect2info>
<title>
Inputs
</title>
<para>
<variablelist>
<varlistentry>
<term>TEMPORARY</term>
<term>TEMP</term>
<listitem>
<para>
If TEMPORARY or TEMP is specified,
the output table is created only within this session, and is
automatically dropped on session exit.
Existing permanent tables with the same name are not visible
(in this session) while the temporary table exists.
Any indexes created on a temporary table are automatically
temporary as well.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">new_table</replaceable></term>
<listitem>
<para>
The name of the new table to be created.
This table must not already exist. However, a temporary table
can be created that has the same name as an existing permanent
table.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
All input fields are described in detail for
All other inputs are described in detail for
<xref linkend="sql-select" endterm="sql-select-title">.
</para>
</refsect2>
<refsect2 id="R2-SQL-SELECTINTO-2">
<refsect2info>
<date>1998-09-22</date>
<date>2001-03-20</date>
</refsect2info>
<title>
Outputs
</title>
<para>
All output fields are described in detail for
<xref linkend="sql-select" endterm="sql-select-title">.
Refer to
<xref linkend="sql-createtable" endterm="sql-createtable-title">
and
<xref linkend="sql-select" endterm="sql-select-title">
for a summary of possible output messages.
</para>
</refsect2>
</refsynopsisdiv>
<refsect1 id="R1-SQL-SELECTINTO-1">
<refsect1info>
<date>1998-09-22</date>
<date>2001-03-20</date>
</refsect1info>
<title>
Description
</title>
<para>
<command>SELECT INTO</command> creates a new table from the results
of a query. Typically, this
query draws data from an existing table, but any SQL query is allowed.
<command>SELECT INTO</command> creates a new table and fills it
with data computed by a query. The data is not returned to the
client, as it is with a normal <command>SELECT</command>. The new
table's columns have the names and datatypes associated with the
output columns of the <command>SELECT</command>.
<note>
<para>
<xref linkend="sql-createtableas" endterm="sql-createtableas-title">
is functionally equivalent to the <command>SELECT INTO</command> command.
is functionally equivalent to <command>SELECT INTO</command>.
<command>CREATE TABLE AS</command> is the recommended syntax, since
<command>SELECT INTO</command> is not standard. In fact, this form of
<command>SELECT INTO</command> is not available in PL/pgSQL or ecpg,
because they interpret the INTO clause differently.
</para>
</note>
</para>
</refsect1>
<refsect1 id="R1-SQL-SELECTINTO-2">
<title>
Compatibility
</title>
<para>
SQL92 uses <command>SELECT ... INTO</command> to represent selecting
values into scalar variables of a host program, rather than creating
a new table. This indeed is the usage found in PL/pgSQL and ecpg.
The <productname>Postgres</productname> usage of <command>SELECT
INTO</command> to represent table creation is historical. It's best
to use <command>CREATE TABLE AS</command> for this purpose in new code.
(<command>CREATE TABLE AS</command> isn't standard either, but it's
less likely to cause confusion.)
</para>
</refsect1>
</refentry>
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