Is there a way to use trigger to stop INSERT, UPDATE or DELETE from happening?


Yes, raise an exception. Example:

CREATE EXCEPTION noname 'Name cannot be empty';

SET TERM ^ ;

CREATE TRIGGER EMPLOYEE_BIU0 FOR EMPLOYEE
ACTIVE BEFORE INSERT OR UPDATE POSITION 0
AS
BEGIN
if (new.FIRST_NAME = '') then exception noname;
END^

SET TERM ; ^

You can also raise a custom exception message like this:

if (new.FIRST_NAME = '')
then exception noname 'Custom message text';

Please note that exception text is limited to 80 characters in Firebird 1.5 and 1024 characters in Firebird 2.0. Although the engine will accept longer strings, it would silently truncate them to this internal limit.


Do you find this FAQ incorrect or incomplete? Please e-mail us what needs to be changed. To ensure quality, each change is checked by our editors (and often tested on live Firebird databases), before it enters the main FAQ database. If you desire so, the changes will be credited to your name. To learn more, visit our add content page.



All contents are copyright © 2007-2024 FirebirdFAQ.org unless otherwise stated in the text.


Links   Firebird   News   FlameRobin   Powered by FB: Home Inventory   Euchre  
Add content   About  

Categories
 Newbies
 SQL
 Installation and setup
 Backup and restore
 Performance
 Security
 Connectivity and API
 HOWTOs
 Errors and error codes
 Miscellaneous