php works best with MySQL, but it also works with PostgreSQL and any ODBC compliant database. It can also run on any webserver and with any operating system.
For building databases graphically, check out DBDesigner4
http://www.fabforce.net/dbdesigner4/ its opensource, works best with mysql but also works with other databases. can reverse engineer and you can actually graphically build the db.
I like phpMyAdmin for administration of a database, but i like DBDesigner for building them.