create_table.sgml

   <para>
    In the current release of <productname>Postgres</productname> (v6.4), to create a temporary
    table you must create and drop the table by explicit commands.
</tip>
   
   <REFSECT3 ID="R3-SQL-UNIQUECLAUSE-1">
    <REFSECT3INFO>
     <DATE>1998-04-15</DATE>
    </REFSECT3INFO>
    <TITLE>
     UNIQUE clause
    </TITLE>
    <PARA>
     SQL92 specifies some additional capabilities for UNIQUE:
    <para>
     Table Constraint definition
    </PARA>
    <synopsis>
      [ CONSTRAINT name ]
      UNIQUE ( column [, ...] )
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
    </synopsis>
    <para>
     Column Constraint definition
    </para>
    <synopsis>
      [ CONSTRAINT name ]
      UNIQUE
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
    </synopsis>
   </refsect3>
   
   <REFSECT3 ID="R3-SQL-NOTNULL-4">
    <REFSECT3INFO>
     <DATE>1998-04-15</DATE>
    </REFSECT3INFO>
    <TITLE>
     NOT NULL clause
    </TITLE>
    <PARA>
     
     SQL92 specifies some additional capabilities for NOT NULL:
    </PARA>
    <synopsis>
      [ CONSTRAINT name ] NOT NULL 
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
    </synopsis>
   </REFSECT3>
   
<!--
I can't figure out why DEFAULT clause is different from what we already have.
Perhaps because CURRENT_USER and CURRENT_DATE have specific types (currently
the "name" type), if you aren't careful then the types won't match up with
the column. Not our problem...
- Thomas 1998-08-16

   <REFSECT3 ID="R3-SQL-DEFAULTCLAUSE-1">
    <REFSECT3INFO>
     <DATE>1998-04-15</DATE>
    </REFSECT3INFO>
    <TITLE>
     DEFAULT clause
    </TITLE>
    <PARA>
     SQL92 specifies some additional capabilities for the DEFAULT clause.
     A DEFAULT clause is used to set the default value for a column
     or a domain.
    </para>
    <synopsis>
     DEFAULT niladic USER function |
             niladic datetime function |
             NULL
    </synopsis>
   </refsect3>
-->
   
   <REFSECT3 ID="R3-SQL-CONSTRAINT-3">
    <REFSECT3INFO>
     <DATE>1998-04-15</DATE>
    </REFSECT3INFO>
    <TITLE>
     CONSTRAINT clause
    </TITLE>
    <PARA>
     SQL92 specifies some additional capabilities for CONSTRAINTs,
     and also defines assertions and domain constraints.
    </PARA>
    <PARA>
     An assertion is a special type of integrity constraint and share
     the same namespace as other constraints.
     However, an assertion is not necessarily dependent on one
     particular base table as constraints are, so SQL-92 provides the
     CREATE ASSERTION statement as an alternate method for defining a
     constraint:
    </para>
    <synopsis>
     CREATE ASSERTION name CHECK ( condition )
    </synopsis>
    
    <PARA>
     Domain constraints are defined by CREATE DOMAIN or ALTER DOMAIN
     statements:
    </para>
    <PARA>
     Domain constraint: 
    </para>
    <synopsis>
      [ CONSTRAINT name ] 
          CHECK constraint 
          [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
          [ [ NOT ] DEFERRABLE ]
    </synopsis>
    <para>
     Table constraint definition:
    </para>
    <synopsis>
      [ CONSTRAINT name ] 
        { PRIMARY KEY constraint | 
          FOREIGN KEY constraint | 
          UNIQUE constraint | 
          CHECK constraint }
          [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
          [ [ NOT ] DEFERRABLE ]</synopsis>
    <para>
     Column constraint definition:
    </para>
    <synopsis>
     [ CONSTRAINT name ] 
        { NOT NULL constraint |
          PRIMARY KEY constraint | 
          FOREIGN KEY constraint | 
          UNIQUE constraint | 
          CHECK constraint }  
          [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
          [ [ NOT ] DEFERRABLE ]
    </synopsis>
    <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>
	 means that the Constraint must be checked for
	 violation of its rule after the execution of every SQL statement.
	</para>
       </listitem>
      </varlistentry>
      <varlistentry>
       <term>DEFERRABLE</term>
       <listitem>
	<para>
	 means that checking of the Constraint may be deferred
	 until some later time, but no later than the end of the current
	 transaction.
	</para>
       </listitem>
      </varlistentry>
     </variablelist>
    </para>
    <para>
     The constraint mode for every Constraint always has an initial
     default value which is set for that Constraint at the beginning
     of a transaction.
     <variablelist>
      <varlistentry>
       <term>INITIALLY IMMEDIATE</term>
       <listitem>
	<para>
	 means that, as of the start of the transaction,
	 the Constraint must be checked for violation of its rule after the
	 execution of every SQL statement.
	</para>
       </listitem>
      </varlistentry>
      <varlistentry>
       <term>INITIALLY DEFERRED</term>
       <listitem>
	<para>
	 means that, as of the start of the transaction,
	 checking of the Constraint may be deferred until some later time,
	 but no later than the end of the current transaction.</para>
       </listitem>
      </varlistentry>
     </variablelist>
    </para>
   </refsect3>
   
   
   <REFSECT3 ID="R3-SQL-CHECK-4">
    <REFSECT3INFO>
     <DATE>1998-04-15</DATE>
    </REFSECT3INFO>
    <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:
    </para>
    <synopsis>
     [ CONSTRAINT name ] 
      CHECK ( VALUE condition ) 
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
    </synopsis>
    <para>
     column constraint definition:
    </para>
    <synopsis>
      [ CONSTRAINT name ] 
      CHECK ( VALUE condition ) 
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
    </synopsis>
<!--
    <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">
    <REFSECT3INFO>
     <DATE>1998-04-15</DATE>
    </REFSECT3INFO>
    <TITLE>
     PRIMARY KEY clause
    </TITLE>
    <PARA>
     SQL92 specifies some additional capabilities for PRIMARY KEY:
    </para>
    <PARA>
     Table Constraint definition:
    </para>
    <synopsis>
      [ CONSTRAINT name ] 
      PRIMARY KEY ( column [, ...] ) 
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
    </synopsis>
    <para>
     Column Constraint definition: 
    </para>
    <synopsis>
      [ CONSTRAINT name ] 
      PRIMARY KEY 
      [ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
      [ [ NOT ] DEFERRABLE ]
    </synopsis>
   </refsect3>
  </refsect2>
 </refsect1>
</refentry>

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