Salesforce Apex Triggers - How to check if field is included in update trigger?

Question

I would really appreciate if someone can guide me to check if a particular field is included in update call inside a before/after update trigger. Many thanks.

Answer 1

All the fields are present in the trigger so, to ascertain if a specific field had been modified you have to retrieve a previous version of the row using oldMap which is Map<ID, sObject> and compare the values in old and new. For example:

trigger CaseOnParticularFieldUpdate on Case (before update) {

    for (Case c: Trigger.new) {

        Case oldCase = Trigger.oldMap.get(c.ID);

        if (c.Field != oldCase.Field) {

            // field was updated, do some magic here

        }

    }

}

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