FirebirdSQL logo
 SQL Language StructureCommon Language Elements 

Creating and Administering Domains

A domain is created with the DDL statement CREATE DOMAIN.

Short Syntax
CREATE DOMAIN name [AS] <type>
  [DEFAULT {<literal> | NULL | <context_var>}]
  [NOT NULL] [CHECK (<condition>)]
  [COLLATE <collation>]
See also

CREATE DOMAIN in the Data Definition (DDL) Statements chapter.

Altering a Domain

To change the attributes of a domain, use the DDL statement ALTER DOMAIN.With this statement you can:

  • rename the domain

  • change the data type

  • drop the current default value

  • set a new default value

  • drop the NOT NULL constraint

  • set the NOT NULL constraint

  • drop an existing CHECK constraint

  • add a new CHECK constraint

Short Syntax
ALTER DOMAIN name
  [{TO new_name}]
  [{SET DEFAULT { <literal> | NULL | <context_var> } |
    DROP DEFAULT}]
  [{SET | DROP} NOT NULL ]
  [{ADD [CONSTRAINT] CHECK (<dom_condition>) |
    DROP CONSTRAINT}]
  [{TYPE <datatype>}]
Example
ALTER DOMAIN STORE_GRP SET DEFAULT -1;

When changing a domain, its dependencies must be taken into account: whether there are table columns, any variables, input and/or output parameters with the type of this domain declared in the PSQL code.If you change domains in haste, without carefully checking them, your code may stop working!

Important

When you convert data types in a domain, you must not perform any conversions that may result in data loss.Also, for example, if you convert VARCHAR to INTEGER, check carefully that all data using this domain can be successfully converted.
See also

ALTER DOMAIN in the Data Definition (DDL) Statements chapter.