Lesson: 24 | Prevents users to delete Accounts with related opportunities

Code

trigger AccountTrigger on Account (before delete) {
    List<Opportunity> relatedOPPList = [SELECT Id FROM Opportunity WHERE AccountId IN: Trigger.old];
    
    if(relatedOppList.size()!=0){
        Trigger.old[0].addError('An account with an opportunity can not be deleted');
    }
   
}

Video