能帮我解释一下下面的代码么？
try {
            db.connectDB();
            String sql = "";
            sql = "select t.* from question t  order by question_id";
            ExtList elist = db.queryToElist(sql);
            
            this.setResult(elist);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally{
            db.disconnectDB();
        }