Trigger Syntax

To define a trigger, use the following syntax:

1trigger TriggerName on ObjectName (trigger_events) {
2                     code_block
3                     }

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

A trigger invoked by an insert, delete, or update of a recurring event or recurring task results in a runtime error when the trigger is called in bulk from the Lightning Platform API.
Suppose that you use an after-insert or after-update trigger to change ownership of leads, contacts, or opportunities. If you use the API to change record ownership, or if a Lightning Experience user changes a record’s owner, no email notification is sent. To send email notifications to a record’s new owner, set the triggerUserEmail property in DMLOptions to true.

Note

For example, the following code defines a trigger for the before insert and before update events on the Account object:

1trigger myAccountTrigger on Account (before insert, before update) {
2    // Your code here
3}

The code block of a trigger cannot contain the static keyword. Triggers can only contain keywords applicable to an inner class. In addition, you do not have to manually commit any database changes made by a trigger. If your Apex trigger completes successfully, any database changes are automatically committed. If your Apex trigger does not complete successfully, any changes made to the database are rolled back.

Apex Developer Guide

Trigger Syntax