SFDCWallah

Before Trigger:

• When you save a record (insert / update) Salesforce fires a DML statement to its database, internally.
• All the code written in the “before update” triggers, executes BEFORE that DML is committed to Salesforce Database.
• In case of update or validate record values before they’re saved to the database in the same object.
• Hence if you are trying to update any value in the record, on which the trigger is fired, you need not write an update call, specifically.
• Fields like id,formula fields won’t be available in before insert triggers as well.

After Trigger:

• Insert/Update related object, not the same object.
• Notification Email.
• used to access field values that are set by the system (such as a record’s Id or LastModifiedDate field)

Here you can see a simple example to differentiate the values we get in before and after insert trigger.

Trigger:

Trigger Handler:

After inserting two Accounts from Anonymous Window, Following values i m getting.

• Here you can see id field is null is before insert.

• Trigger.new is returning a list of Account records.

• Trigger.NewMap is returning a Map<id,Account>.

• Note : The records that fire the after trigger are read-only.
• So if it is a before insert trigger, you can’t query those records. Some thing like:
• List<Account> accList = [Select Id, Name From Account Where Id in :Trigger.New];
• won’t work in before insert trigger because the records are not there yet. But it will work in before update trigger.