I had developed a nice utility which uses PHP to connect to a database and generates stored procedures which reads all records, reads a single record with input parameters based on a primary key, updates based on the primary key and deletes based on the primary key. Have a look here http://www.it-iss.com/mysql/phpcrud-for-mysql/
some sort of visual designing or auto completion is required.
I can't imagine how visual designing can be used for writing stored procedures because stored procedures is computer language code - it's not like a database table structure that you can visually represent - or maybe I am missing something?
As to auto-completion you can use one of the mysql database management software, a free one with auto-completion is HeidiSQL, a paid one is SQLYog - perhaps others can add their favourites.