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 com-
              mands; 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 columns 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 any-
       thing you couldn't do by dropping and recreating the domain.  However, a superuser can alter ownership of any domain any-
       way.)

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                                  2011-09-22                                            ALTER DOMAIN(7)