|Oracle9i SQL Reference
Release 2 (9.2)
Part Number A96540-02
TRIGGER statement to enable, disable, or compile a database trigger.
This statement does not change the declaration or definition of an existing trigger. To redeclare or redefine a trigger, use the
The trigger must be in your own schema or you must have
ANY TRIGGER system privilege.
In addition, to alter a trigger on
DATABASE, you must have the
TRIGGER system privilege.
CREATE TRIGGER for more information on triggers based on
Specify the schema containing the trigger. If you omit
schema, then Oracle assumes the trigger is in your own schema.
Specify the name of the trigger to be altered.
ENABLE to enable the trigger. You can also use the
TRIGGERS clause of
TABLE to enable all triggers associated with a table.
DISABLE to disable the trigger. You can also use the
TRIGGERS clause of
TABLE to disable all triggers associated with a table.
new_name to rename the trigger. Oracle renames the trigger and leaves it in the same state it was in before being renamed.
When you rename a trigger, Oracle rebuilds the remembered source of the trigger in the
COMPILE to explicitly compile the trigger, whether it is valid or invalid. Explicit recompilation eliminates the need for implicit run-time recompilation and prevents associated run-time compilation errors and performance overhead.
Oracle first recompiles objects upon which the trigger depends, if any of these objects are invalid. If Oracle recompiles the trigger successfully, then the trigger becomes valid.
During recompilation, Oracle drops all persistent compiler switch settings, retrieves them again from the session, and stores them at the end of compilation. To avoid this process, specify the
If recompiling the trigger results in compilation errors, then Oracle returns an error and the trigger remains invalid. You can see the associated compiler error messages with the SQL*Plus command
DEBUG to instruct the PL/SQL compiler to generate and store the code for use by the PL/SQL debugger.
SETTINGS to prevent Oracle from dropping and reacquiring compiler switch settings. With this clause, Oracle preserves the existing settings and uses them for the recompilation.
If you specify both
SETTINGS, Oracle sets the persistently stored value of the
PLSQL_COMPILER_FLAGS parameter to
DEBUG. No other compiler switch values are changed.
PL/SQL User's Guide and Reference and Oracle9i Application Developer's Guide - Fundamentals for more information on the interaction of the
The sample schema
hr has a trigger named
update_job_history created on the
employees table. The trigger is fired whenever an
UPDATE statement changes an employee's
job_id. The trigger inserts into the
job_history table a row that contains the employee's ID, begin and end date of the last job, and the job ID and department.
When this trigger is created, Oracle enables it automatically. You can subsequently disable the trigger with the following statement:
When the trigger is disabled, Oracle does not fire the trigger when an
UPDATE statement changes an employee's job.
After disabling the trigger, you can subsequently enable it with the following statement:
After you reenable the trigger, Oracle fires the trigger whenever an employee's job changes as a result of an
UPDATE statement. If an employee's job is updated while the trigger is disabled, then Oracle does not automatically fire the trigger for this employee until another transaction changes the