ALTER 
DOMAIN(7) 						   SQL Commands 						   ALTER DOMAIN(7)

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
       ALTER DOMAIN name
	   SET SCHEMA new_schema

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 can only SET NOT NULL when the col-
	      umns using the domain contain no null values.

       ADD domain_constraint
	      This  form  adds	a new constraint to a domain using the same syntax as CREATE DOMAIN [create_domain(7)].  This will only succeed if
	      all columns using the domain satisfy the new constraint.

       DROP CONSTRAINT
	      This form drops constraints on a domain.

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

       SET SCHEMA
	      This form changes the schema of the domain. Any constraints associated with the domain are moved into the new schema as well.

       You must own the domain to use ALTER DOMAIN.  To change the schema of a domain, you must also have CREATE privilege on the new schema.	To
       alter  the  owner,  you	must  also  be a direct or indirect member of the new owning role, and that role must have CREATE privilege on the
       domain's schema. (These restrictions enforce that altering the owner doesn't do anything you couldn't do by  dropping  and  recreating  the
       domain.	However, a superuser can alter ownership of any domain anyway.)

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.

       new_schema
	      The new schema for the domain.

NOTES

       Currently,  ALTER  DOMAIN ADD CONSTRAINT and ALTER DOMAIN SET NOT NULL will fail if the named domain or any derived domain is used within a
       composite-type column of any table in the database. They should eventually be improved to be able to verify the	new  constraint  for  such
       nested columns.

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;

       To move the domain into a different schema:

       ALTER DOMAIN zipcode SET SCHEMA customers;

COMPATIBILITY

       ALTER DOMAIN conforms to the SQL standard, except for the OWNER and SET SCHEMA variants, which are PostgreSQL extensions.

SEE ALSO

       CREATE DOMAIN [create_domain(7)], DROP DOMAIN [drop_domain(7)]

SQL - Language Statements					    2010-05-14							   ALTER DOMAIN(7)