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

Human Resources Management System

A Human Resources Management System (HRMS) is a software application that supports many functions of a company's Human Resources department, including benefits administration, payroll,...

How To Defend Yourself Against Identity Theft

Almost every worldwide government agency responsible for identity theft issues will tell you the same thing: The first step to fighting identity theft is...

Infographic

An infographic is a visual representation of information or data. It combines the words information and graphic and includes a collection of imagery, charts,...

Phishing

What is phishing? Phishing is a type of cybercrime in which victims are contacted by email, telephone, or text message by an attacker posing as...

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...