When a database object is disabled, the database server ignores it during the execution of an INSERT, DELETE, SELECT, or UPDATE statement. A disabled constraint is not enforced, a disabled index is not updated, and a disabled trigger is not executed when the trigger event takes place. When you disable constraints and unique indexes, any data manipulation statement that violates the restriction of the constraint or unique index succeeds (that is, the target row is changed), and the database server does not return an error message.
You can use the disabled mode to add a new constraint or new unique index to an existing table, even if some rows in the table do not satisfy the new integrity specification. Disabling can also be efficient in LOAD operations.
For information on adding a constraint, see Adding a Constraint That Existing Rows Violate (IDS) in the ALTER TABLE statement. For information on adding a unique index, see Adding a Unique Index When Duplicate Values Exist in the Column in the CREATE INDEX statement.
Enterprise Edition Home | Express Edition Home | [ Top of Page | Previous Page | Next Page | Contents | Index ]