select_into.sgml

postgresql8.3.4源码,开源数据库

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<refentry id="SQL-SELECTINTO">
 <refmeta>
  <refentrytitle id="SQL-SELECTINTO-TITLE">SELECT INTO</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>SELECT INTO</refname>
  <refpurpose>define a new table from the results of a query</refpurpose>
 </refnamediv>

 <indexterm zone="sql-selectinto">
  <primary>SELECT INTO</primary>
 </indexterm>

 <refsynopsisdiv>
<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> [, ...] ]
    [ HAVING <replaceable class="PARAMETER">condition</replaceable> [, ...] ]
    [ { UNION | INTERSECT | EXCEPT } [ ALL ] <replaceable class="PARAMETER">select</replaceable> ]
    [ ORDER BY <replaceable class="parameter">expression</replaceable> [ ASC | DESC | USING <replaceable class="parameter">operator</replaceable> ] [ NULLS { FIRST | LAST } ] [, ...] ]
    [ LIMIT { <replaceable class="PARAMETER">count</replaceable> | ALL } ]
    [ OFFSET <replaceable class="PARAMETER">start</replaceable> ]
    [ FOR { UPDATE | SHARE } [ OF <replaceable class="parameter">table_name</replaceable> [, ...] ] [ NOWAIT ] [...] ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <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 data types associated with the
   output columns of the <command>SELECT</command>.
  </para>
 </refsect1>
  
 <refsect1>
  <title>Parameters</title>

  <variablelist>
  <varlistentry>
   <term><literal>TEMPORARY</literal> or <literal>TEMP</literal></term>
   <listitem>
    <para>
     If specified, the table is created as a temporary table.  Refer
     to <xref linkend="sql-createtable"
     endterm="sql-createtable-title"> for details.
    </para>
   </listitem>
  </varlistentry>

   <varlistentry>
    <term><replaceable class="PARAMETER">new_table</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of the table to be created.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>

  <para>
   All other parameters are described in detail under <xref
   linkend="sql-select" endterm="sql-select-title">.
  </para>
 </refsect1>

 <refsect1>
  <title>Notes</title>

  <para>
   <xref linkend="sql-createtableas"
   endterm="sql-createtableas-title"> is functionally similar to
   <command>SELECT INTO</command>.  <command>CREATE TABLE AS</command>
   is the recommended syntax, since this form of <command>SELECT
   INTO</command> is not available in <application>ECPG</application>
   or <application>PL/pgSQL</application>, because they interpret the
   <literal>INTO</literal> clause differently. Furthermore,
   <command>CREATE TABLE AS</command> offers a superset of the
   functionality provided by <command>SELECT INTO</command>.
  </para>

  <para>
   Prior to <productname>PostgreSQL</> 8.1, the table created by
   <command>SELECT INTO</command> included OIDs by default. In
   <productname>PostgreSQL</productname> 8.1, this is not the case
   &mdash; to include OIDs in the new table, the <xref
   linkend="guc-default-with-oids"> configuration variable must be
   enabled. Alternatively, <command>CREATE TABLE AS</command> can be
   used with the <literal>WITH OIDS</literal> clause.
  </para>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   Create a new table <literal>films_recent</literal> consisting of only
   recent entries from the table <literal>films</literal>:

<programlisting>
SELECT * INTO films_recent FROM films WHERE date_prod &gt;= '2002-01-01';
</programlisting>
  </para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   The SQL standard 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 <application>ECPG</application> (see <xref linkend="ecpg">) and
   <application>PL/pgSQL</application> (see <xref linkend="plpgsql">).
   The <productname>PostgreSQL</productname> usage of <command>SELECT
   INTO</command> to represent table creation is historical.  It is
   best to use <command>CREATE TABLE AS</command> for this purpose in
   new code.
  </para>
 </refsect1>

 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="sql-createtableas" endterm="sql-createtableas-title"></member>
  </simplelist>
 </refsect1>
</refentry>