Looking at the Examulator database schema for Moodle 3.5, it looks like Description is in the mdl_user_info_field table not the mdl_user table, so maybe try making that change in the query. Another thing you can try is to create a test template with a query like SELECT * FROM mdl_user WHERE mdl_userid=[insert a user id who you know has a mobile phone on their profile]. This will select all fields in that table for that user. Put that template on a page, then go into the View Page Source on your browser and search for the name of your template and its info and verify that the phone2 field is in the dataset or if that field has a different name.