WHAT IS APEX TRIGGER IN SALESFORCE?

Apex triggers are used to manage records in Salesforce. It enables us to perform operations before or after the event is completed. In the “before event” we generally perform validations to prevent wrong entry into the database. In the “after event” we perform operations such as creating or updating a related record. The trigger is a very powerful mechanism using which we can do operations such as executing SOQL, executing DML operations, calling apex class methods.

A trigger is Apex code that executes before or after the following types of operations:

insert

update

delete

merge

upsert

undelete

TRIGGER SYNTAX:

trigger triggerName on objectName (trigger events) {

   // Block of code

}

where "trigger events" can be a comma-separated list of one or more of the following events:

before insert

before update

before delete

after insert

after update

after delete

after undelete

Note:

1) upsert triggers fire both before and after insert or before and after update triggers as appropriate.

2) merge triggers fire both before and after delete for the losing records, and both before and after update triggers for the winning record.