alter_domain

ALTER DOMAIN()			 SQL Commands		       ALTER DOMAIN()



NAME
       ALTER DOMAIN - change the definition of a domain


SYNOPSIS
       ALTER DOMAIN name
	   { SET DEFAULT expression | DROP DEFAULT }
       ALTER DOMAIN name
	   { SET | DROP } NOT NULL
       ALTER DOMAIN name
	   ADD domain_constraint
       ALTER DOMAIN name
	   DROP CONSTRAINT constraint_name [ RESTRICT | CASCADE ]
       ALTER DOMAIN name
	   OWNER TO new_owner



DESCRIPTION
       ALTER  DOMAIN changes the definition of an existing domain.  There are
       several sub-forms:

       SET/DROP DEFAULT
	      These forms set or remove the default value for a domain.	 Note
	      that defaults only apply to subsequent INSERT commands; they do
	      not affect rows already in a table using the domain.

       SET/DROP NOT NULL
	      These forms change whether a domain is  marked  to  allow	 NULL
	      values or to reject NULL values. You may only SET NOT NULL when
	      the columns using the domain contain no null values.

       ADD domain_constraint
	      This form adds a new constraint to a domain using the same syn-
	      tax  as  CREATE DOMAIN [create_domain(7)].  This will only suc-
	      ceed if all columns using	 the  domain  satisfy  the  new	 con-
	      straint.

       DROP CONSTRAINT
	      This form drops constraints on a domain.

       OWNER  This  form  changes  the	owner  of the domain to the specified
	      user.

       You must own the domain to use ALTER DOMAIN; except for	ALTER  DOMAIN
       OWNER, which may only be executed by a superuser.


PARAMETERS
       name   The  name	 (possibly schema-qualified) of an existing domain to
	      alter.

       domain_constraint
	      New domain constraint for the domain.

       constraint_name
	      Name of an existing constraint to drop.

       CASCADE
	      Automatically drop objects that depend on the constraint.

       RESTRICT
	      Refuse to drop  the  constraint  if  there  are  any  dependent
	      objects. This is the default behavior.

       new_owner
	      The user name of the new owner of the domain.


EXAMPLES
       To add a NOT NULL constraint to a domain:

       ALTER DOMAIN zipcode SET NOT NULL;


       To remove a NOT NULL constraint from a domain:

       ALTER DOMAIN zipcode DROP NOT NULL;



       To add a check constraint to a domain:

       ALTER DOMAIN zipcode ADD CONSTRAINT zipchk CHECK (char_length(VALUE) = 5);



       To remove a check constraint from a domain:

       ALTER DOMAIN zipcode DROP CONSTRAINT zipchk;



COMPATIBILITY
       The  ALTER  DOMAIN  statement is compatible with SQL99, except for the
       OWNER variant, which is a PostgreSQL extension.



SQL - Language Statements	  2008-01-03		       ALTER DOMAIN()