Trigger

(n.) In a DBMS, a trigger is a SQL procedure that initiates an action (i.e., fires an action) when an event (INSERT, DELETE or UPDATE) occurs. Since triggers are event-driven specialized procedures, they are stored in and managed by the DBMS. A trigger cannot be called or executed; the DBMS automatically fires the trigger as a result of a data modification to the associated table. Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion.

Each trigger is attached to a single, specified table in the database.

Triggers can be viewed as similar to stored procedures in that both consist of procedural logic that is stored at the database level. Stored procedures, however, are not event-drive and are not attached to a specific table as triggers are. Stored procedures are explicitly executed by invoking a CALL to the procedure while triggers are implicitly executed. In addition, triggers can also execute stored procedures.

A trigger can also contain INSERT, UPDATE and DELETE logic within itself, so when the trigger is fired because of data modification it can also cause another data modification, thereby firing another trigger. A trigger that contains data modification logic within itself is called a nested trigger.

(v.) To initiate an action.

Vangie Beal
Vangie Beal
Vangie Beal is a freelance business and technology writer covering Internet technologies and online business since the late '90s.

Related Articles

@ Sign

Pronounced at sign or simply as at, this symbol is used in e-mail addressing to separate the user' name from the user's domain name,...

Munging

(MUHN-jing) Munging (address munging), is the act of altering an email address posted on a Web page to make it unreadable to bots and...

How to Create an RSS Feed

In the second installment of RSS how-to, we look at some of the nonrequired (optional) channel and item tags, discuss RSS specifications in-depth and...

Dictionary Attack

(n.) (1) A method used to break security systems, specifically password-based security systems, in which the attacker systematically tests all possible passwords beginning with...

ScalaHosting

ScalaHosting is a leading managed hosting provider that offers secure, scalable, and affordable...

HRIS

Human resources information system (HRIS) solutions help businesses manage multiple facets of their...

Best Managed Service Providers...

In today's business world, managed services are more critical than ever. They can...