Delete child record if a field of parent is updated using trigger

Question

My code is:

    trigger ClassCustomStatus on Class__c (before update) {
        Set<Id> classSet = new Set<Id>();
        for(Class__c c : Trigger.new){
            if(c.Custom_Status__c == 'Reset'){
                classSet.add(c.Id);
            }
        }
        list<student__C> s = [SELECT id FROM Student__c WHERE class__c IN:classSet];
        Delete s;
    }

Here I am getting one exception this:

How can delete child records which are from student__c And How can I update a field of parent which is Class__c Please help

Answer 1

Use after update to make sure that the record isn't already pending any changes. The rest of your code is fine.