I have two custom objects, Question__c and Response__c. There is a lookup field named Related_Question__c on the Response__c object to relate the two. In my VF controller I have two Lists, one for each object. My objective is to find all records in the Question List that do not have a match in the Response List (ie questions that haven't been answered yet).
I believe I need to use a map for this but am unsure of exactly how to accomplish this. Any advice would be appreciated. Thanks in advance.
Here's what I have so far to build the two Lists:
List <Question__c> questions = [select Id, Name From Question__c]; List <Response__c> questionResponses = [select Id, Name, Related_Question__c From Response__c Where Related_Question__c IN: questions};