sfdc-learn #17: Salesforce Trigger : Prevent contact records delete (automatically as cascade delete) when account deleted as Cascade delete.

Requirement: Prevent to delete contact record when account deleted as Cascade delete.

Implementation: 

 Using apex trigger, In before delete, set deleted account's  associated contact records AccountId field to null..

Refer below apex trigger code :

trigger accountTrigger on Account (before delete){

    List<Contact> conToUpdateList =  new List<Contact>();

    Set<Id> accountIdSet =  new Set<Id>();

   

    for(Account acc : trigger.old){

        accountIdSet.add(acc.Id);

    }

    if(!accountIdSet.isEmpty()){

        List<Contact> contactList = [SELECT id

                                    FROM Contact

                                    WHERE AccountId In: accountIdSet];

        for(Contact con : contactList){

            con.AccountId = null;

            conToUpdateList.add(con);

        }

        if(!conToUpdateList.isEmpty()){

            update conToUpdateList;

        }

    }

}