class="parameter">referential_action</replaceable> in a <literal>FOREIGN KEY</literal>/<literal>REFERENCES</literal> constraint is:</phrase>

{ NO ACTION | RESTRICT | CASCADE | SET NULL [ ( <replaceable class="parameter">column_name</replaceable> [, ... ] ) ] | SET DEFAULT [ ( <replaceable class="parameter">column_name</replaceable> [, ... ] ) ] }
</synopsis>

 </refsynopsisdiv>

 <refsect1 id="sql-createtable-description">
  <title>Description</title>

  <para>
   <command>CREATE TABLE</command> will create a new, initially empty table
   in the current database. The table will be owned by the user issuing the
   command.
  </para>

  <para>
   If a schema name is given (for example, <literal>CREATE TABLE
   myschema.mytable ...</literal>) then the table is created in the specified
   schema.  Otherwise it is created in the current schema.  Temporary
   tables exist in a special schema, so a schema name cannot be given
   when creating a temporary table.  The name of the table must be
   distinct from the name of any other relation (table, sequence, index, view,
   materialized view, or foreign table) in the same schema.
  </para>

  <para>
   <command>CREATE TABLE</command> also automatically creates a data
   type that represents the composite type corresponding
   to one row of the table.  Therefore, tables cannot have the same
   name as any existing data type in the same schema.
  </para>

  <para>
   The optional constraint clauses specify constraints (tests) that
   new or updated rows must satisfy for an insert or update operation
   to succeed.  A constraint is an SQL object that helps define the
   set of valid values in the table in various ways.
  </para>

  <para>
   There are two ways to define constraints: table constraints and
   column constraints.  A column constraint is defined as part of a
   column definition.  A table constraint definition is not tied to a
   particular column, and it can encompass more than one column.
   Every column constraint can also be written as a table constraint;
   a column constraint is only a notational convenience for use when the
   constraint only affects one column.
  </para>

  <para>
   To be able to create a table, you must have <literal>USAGE</literal>
   privilege on all column types or the type in the <literal>OF</literal>
   clause, respectively.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>

   <varlistentry id="sql-createtable-temporary">
    <term><literal>TEMPORARY</literal> or <literal>TEMP</literal></term>
    <listitem>
     <para>
      If specified, the table is created as a temporary table.
      Temporary tables are automatically dropped at the end of a
      session, or optionally at the end of the current transaction
      (see <literal>ON COMMIT</literal> below).  The default
      search_path includes the temporary schema first and so identically
      named existing permanent tables are not chosen for new plans
      while the temporary table exists, unless they are referenced
      with schema-qualified names. Any indexes created on a temporary
      table are automatically temporary as well.
     </para>

     <para>
      The <link linkend="autovacuum">autovacuum daemon</link> cannot
      access and therefore cannot vacuum or analyze temporary tables.
      For this reason, appropriate vacuum and analyze operations should be
      performed via session SQL commands.  For example, if a temporary
      table is going to be used in complex queries, it is wise to run
      <command>ANALYZE</command> on the temporary table after it is populated.
     </para>

     <para>
      Optionally, <literal>GLOBAL</literal> or <literal>LOCAL</literal>
      can be written before <literal>TEMPORARY</literal> or <literal>TEMP</literal>.
      This presently makes no difference in <productname>PostgreSQL</productname>
      and is deprecated; see
      <xref linkend="sql-createtable-compatibility"/> below.
     </para>
    </listitem>