Changes to joining website

Hi, I currently have a form [login to view URL] which calls on files js/[login to view URL] and request/[login to view URL] These are all functional and can be viewed to see what changes need to be made for this project. The changes are to be made to [login to view URL], js/[login to view URL] and request/[login to view URL] TASK 1 - The change on [login to view URL] involves the addition of functionality to the field 'school_id'. This field is a dropdown menu, showing the field 'school_name' from the table member_school (mysql dump attached). The school_id is the value for the name. This needs to be inserted in to the 'school_id' field in the members table (mysql dump attached). TASK 2 - The member_display_name field in the form on [login to view URL] is a non-mandatory field. However, I would like validation applied so that if a user does type a value into this field, it must be a value that does not already exist in the member_display_name field in the members table. (similar logic to the member_username except that the member_username is a mandatory field and member_display_name is a non-mandatory field). Thanks, Dave