触发不更新和删除数据

I have a table tblDHColl with fields ProjectID, HoleID, X, Y, Z and Locked (bit datatype). I want to create a trigger to prevent any update or delete for the holes where Locked=1 or 'True'. I want to allow any other updations or deletions of the data if Locked field is 0 or 'false' for any hole. Since I am new to triggers, please advise me how to create a trigger on tblDHColl.I have a table tblDHColl with fields ProjectID,