phpMyAdmin is a feature-rich tool developed in PHP, which will provide you with 100 % control over a MySQL database. You could do absolutely everything - create fields, rows and tables, delete them or change their data, export or import a whole database or just a particular part of it, and execute MySQL commands. The tool is vital if you want to switch web hosting companies, simply because you can easily generate a full backup of a database in a variety of formats (SQL, CSV, XML). You will end up with a single file that contains the entire content of the database, so you could download it from the current provider, upload it to the server of the new one and import it via the same tool on their end. Your website shall look exactly the same, because all script applications store their content within a database. With phpMyAdmin you could also conveniently search and replace content of your preference across the entire web site - a word, an expression or a link, for instance.