postgresql/doc/src/sgml/ref/create_table_as.sgml

<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table_as.sgml,v 1.8 2001/10/22 18:14:47 petere Exp $
Postgres documentation
-->

<refentry id="SQL-CREATETABLEAS">
 <refmeta>
  <refentrytitle>CREATE TABLE AS</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>CREATE TABLE AS</refname>
  <refpurpose>create a new table from the results of a query</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
CREATE [ [ LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name</replaceable> [ (<replaceable>column_name</replaceable> [, ...] ) ]
    AS <replaceable>query</replaceable>
  </synopsis>
 </refsynopsisdiv>
  
 <refsect1>
  <refsect1info>
   <date>2001-03-20</date>
  </refsect1info>
  <title>
   Description
  </title>
  <para>
   <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 data types associated with the
   output columns of the <command>SELECT</command> (except that you
   can override the column names by giving an explicit list of new
   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 query just once to fill the new table
   initially.  The new table will not track subsequent changes to the
   source tables of the query.  In contrast, a view re-evaluates the
   underlying <command>SELECT</command> statements whenever it is
   queried.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>
   
  <variablelist>
   <varlistentry>
    <term><literal>[LOCAL] TEMPORARY</> or <literal>[LOCAL] TEMP</></term>
    <listitem>
     <para>
      If specified, the table is created as a temporary table.
      Temporary tables are automatically dropped at the end of a
      session.  Existing persistent tables with the same name are not
      visible to the current session while the temporary table exists.
      Any indexes created on a temporary table are automatically
      temporary as well.
     </para>

     <para>
      The <literal>LOCAL</literal> word is optional.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable>table_name</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>

   <varlistentry>
    <term><replaceable>column_name</replaceable></term>
    <listitem>
     <para>
      The name of a column in the new table. Multiple column names can
      be specified using a comma-delimited list of column names.  If
      column names are not provided, they are taken from the output
      column names of the query.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable>query</replaceable></term>
    <listitem>
     <para>
      A query statement (that is, a <command>SELECT</command>
      command).  Refer to
      <xref linkend="sql-select">
      for a description of the allowed syntax.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Diagnostics</title>

  <para>
   Refer to <xref linkend="sql-createtable"> and
   <xref linkend="sql-select">
   for a summary of possible output messages.
  </para>
 </refsect1>

 <refsect1>
  <title>Notes</title>

  <para>
   This command is functionally equivalent to <xref
   linkend="sql-selectinto">, but it is preferred since it is less
   likely to be confused with other uses of the <command>SELECT
   ... INTO</command> syntax.
  </para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   This command is modeled after an <productname>Oracle</productname>
   feature.  There is no command with equivalent functionality in
   SQL92 or SQL99.  However, a combination of <literal>CREATE
   TABLE</literal> and <literal>INSERT ... SELECT</literal> can
   accomplish the same thing with little more effort.
  </para>
 </refsect1>

 <refsect1>
  <title>History</title>

  <para>
   The <command>CREATE TABLE AS</command> command has been available
   since <productname>PostgreSQL</productname> 6.3.
  </para>
 </refsect1>

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

  <simplelist type="inline">
   <member><xref linkend="sql-createtable"></member>
   <member><xref linkend="sql-createview"></member>
   <member><xref linkend="sql-select"></member>
   <member><xref linkend="sql-selectinto"></member>
  </simplelist>
 </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:
-->