create_table.sgml

     <synopsis>
[ CONSTRAINT <replaceable>name</replaceable> ] { PRIMARY KEY ( <replaceable class="parameter">column</replaceable>, ... ) | FOREIGN KEY <replaceable>constraint</replaceable> | UNIQUE <replaceable>constraint</replaceable> | CHECK <replaceable>constraint</replaceable> }
    [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
    [ [ NOT ] DEFERRABLE ]
     </synopsis>
    </para>

    <para>
     Column constraint definition:

     <synopsis>
[ CONSTRAINT <replaceable>name</replaceable> ] { NOT NULL | PRIMARY KEY | FOREIGN KEY <replaceable>constraint</replaceable> | UNIQUE | CHECK <replaceable>constraint</replaceable> }  
    [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
    [ [ NOT ] DEFERRABLE ]
     </synopsis>
    </para>

    <para>
     A CONSTRAINT definition may contain one deferment attribute
     clause and/or one initial constraint mode clause, in any order.
     <variablelist>
      <varlistentry>
       <term>NOT DEFERRABLE</term>
       <listitem>
	<para>
         The constraint must be checked at the end of each statement.
         SET CONSTRAINTS ALL DEFERRED will have no effect on this type
         of constraint.
	</para>
       </listitem>
      </varlistentry>
      <varlistentry>
       <term>DEFERRABLE</term>
       <listitem>
	<para>
         This controls whether the constraint can be deferred to the end
         of the transaction. If SET CONSTRAINTS ALL DEFERRED is used or
         the constraint is set to INITIALLY DEFERRED, this will cause
         the foreign key to be checked only at the end of the
         transaction.
	</para>
        <note>
         <para>  
          <command>SET CONSTRAINTS</> changes the foreign key constraint mode
          only for the current transaction.
         </para>
        </note>
       </listitem>
      </varlistentry>
      <varlistentry>
       <term>INITIALLY IMMEDIATE</term>
       <listitem>
	<para>
	 Check constraint only at the end of the transaction. This
	 is the default
	</para>
       </listitem>
      </varlistentry>
      <varlistentry>
       <term>INITIALLY DEFERRED</term>
       <listitem>
	<para>
	 Check constraint after each statement.
	</para>
       </listitem>
      </varlistentry>
     </variablelist>
    </para>
   </refsect3>
   
   
   <refsect3 id="R3-SQL-CHECK-4">
    <title>
     CHECK clause
    </title>
    <para>
     SQL92 specifies some additional capabilities for CHECK in either
table or column constraints.
    </para>
<!--
Constraints associated with domains do not need to be mentioned here,
even though it is the case that a domain constraint may possibly
affect a column or a table.
- Thomas 1998-08-16
    <para>
     A CHECK constraint is either a table constraint, a column
     constraint or a domain constraint.
    </para> 
-->
    <para>
     table constraint definition:
     <synopsis>
[ CONSTRAINT <replaceable>name</replaceable> ] CHECK ( VALUE <replaceable>condition</replaceable> ) 
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
     </synopsis>
    </para>

    <para>
     column constraint definition:
    <synopsis>
[ CONSTRAINT <replaceable>name</replaceable> ] CHECK ( VALUE <replaceable>condition</replaceable> ) 
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
    </synopsis>
    </para>
<!--
   <para>
     domain constraint definition: 
    </para>
    <synopsis>
     [ CONSTRAINT name] 
      CHECK ( VALUE condition ) 
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
    </synopsis>
    <para>
     CHECK domain constraints can be defined in either
     a CREATE DOMAIN statement or an ALTER DOMAIN statement:
    </para>
    <programlisting>
CREATE DOMAIN duration AS SMALLINT 
    CONSTRAINT minutes CHECK (VALUE IN (90,120,180,240)); 

ALTER DOMAIN cities 
    ADD CONSTRAINT new_city CHECK (VALUE LIKE 'L%');
   </programlisting>
-->
   </refsect3>

   <refsect3 id="R3-SQL-PRIMARYKEY-1">
    <title>
     PRIMARY KEY clause
    </title>
    <para>
     SQL92 specifies some additional capabilities for PRIMARY KEY:
    </para>
    <para>
     Table Constraint definition:
     <synopsis>
[ CONSTRAINT <replaceable>name</replaceable> ] PRIMARY KEY ( <replaceable>column</replaceable> [, ...] ) 
    [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
    [ [ NOT ] DEFERRABLE ]
     </synopsis>
    </para>
    <para>
     Column Constraint definition: 
     <synopsis>
[ CONSTRAINT <replaceable>name</replaceable> ] PRIMARY KEY 
    [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
    [ [ NOT ] DEFERRABLE ]
     </synopsis>
    </para>
   </refsect3>

   <refsect3 id="R3-SQL-INHERITANCE-1">
    <title>
     Inheritance
    </title>
    <para>
     Multiple inheritance via the INHERITS clause is a
     <productname>Postgres</productname> language extension.
     SQL99 (but not SQL92) defines single inheritance using a different
     syntax and different semantics.  SQL99-style inheritance is not yet
     supported by <productname>Postgres</productname>.
    </para>
   </refsect3>
  </refsect2>
 </refsect1>
</refentry>

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