phpMyAdmin is a tool intended to handle the administration of MySQL over the Web. It can create, rename, and drop databases, create/drop/alter tables, delete/edit/add fields, execute any SQL statement, manage keys on fields, create dumps of tables and databases, export/import CSV data, and administrate one single database and multiple MySQL servers.
Squarebase is a Web-based interface for MySQL databases. The basic idea is that it builds a database (called the "metabase") that describes the structure of the database. The information in the metabase is used to format lists and forms for browsing and editing the contents of the database.
SynApp2 is a development tool that generates database-backed Web applications by processing your MySQL or Oracle schema definition and producing the Web pages used to manage your data. It does more than an admin tool or file manager by considering table relations as a cohesive whole that drives the generation of a complete application that smoothly integrates your entire database design, complete with PDF reports. It is open, compact, efficient, and compatible with the tools and technologies you’re using now.