(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.
Stay up to date on the latest developments in Internet terminology with a free weekly newsletter from Webopedia. Join to subscribe now.
The following facts and statistics capture the changing landscape of cloud computing and how service providers and customers are keeping up with... Read More »Facts about Computer Science: Education and Jobs
The following computer science facts and statistics provides a quick introduction to the changing trends in education and related careers. Read More »Text Messaging & Chat Abbreviations
From A3 to LOL and ZZZ this guide lists 1,500 text message and online chat abbreviations to help you translate and understand today's texting... Read More »
Learn about each of the five generations of computers and major technology developments that have led to the computing devices that we use... Read More »Computer Architecture Study Guide
Computer architecture provides an introduction to system design basics for most computer science students. Read More »Network Fundamentals Study Guide
Networking fundamentals teaches the building blocks of modern network design. Learn different types of networks, concepts, architecture and... Read More »