What are Triggers in SQL: How to Implement them
With the help of SQL triggers, developers can specify SQL operations that should be carried out automatically whenever a specific event occurs in the database. Examples include inserting a record into one table while updating records in another.
In this article, you will discover SQL triggers, how they operate, and how to utilize them in your database. Learn SQL triggers entirely by following this guide!
How do SQL Triggers work?
Triggers are specific procedures that are event-driven, saved, and handled by the DBMS. A trigger is a particular kind of stored SQL procedure that starts an action—or, more precisely, fires an action—when an event like an INSERT, DELETE, or UPDATE occurs. A trigger can also include INSERT, UPDATE, and DELETE logic, which means that when a data alteration triggers it, it may also result in another data modification, which triggers another trigger. A nested trigger has its own data storage modification logic.
What are Stored Procedures and Triggers?
Both triggers and stored procedures use procedural logic held at the database level. Triggers are often referred to as “a particular sort of stored process.” Stored procedures are not event-driven or connected to a specific table, in contrast to triggers. Each trigger only functions when an INSERT, UPDATE or DELETE event occurs and is specific to one table in the database. A trigger cannot be invoked or executed; instead, it is automatically fired by the DBMS whenever data in the linked table is changed. When creating a trigger, you must provide the modification activity that will activate it.
The following trigger events are accepted:
● INSERT: When a new row is added to the table, as happens when using the INSERT, LOAD DATA, and REPLACE statements, the trigger becomes active.
● UPDATE: trigger becomes active when a row changes, such as through UPDATE statements.
● DELETE: trigger starts working a row anytime it is removed from the table, for instance, by using DELETE and REPLACE commands.
Most of the time, developers utilize triggers to carry out operations like adding data into audit logs and enforcing business rules. Then, as a result of an INSERT, UPDATE, or DELETE event, it is utilized to carry out a specific action.
Working with Triggers and Creating Them
The fundamental procedures to create and change a trigger are as follows:
1. The node for the table to which you wish to add the trigger can be expanded by clicking on it.
2. Right-click the “Trigger” node now and choose “New Trigger.”
3. Enter the new trigger’s query here to open a new query window.
4.” CREATE TRIGGER” should be run.
5. The newly generated trigger will be listed among the other triggers connected to that table.
To summarize, triggers are an essential feature of SQL that allows you to automate specific tasks and maintain data consistency in your database. Following the steps above, you can easily implement triggers in your SQL database and take advantage of their many benefits. To know more, visit Education Nest.