JDeveloper's database development tools are particularly strong. The database navigator provides a graphical management interface, and it supports plenty of databases out of the box: Oracle, DB2, Derby, MySQL, SQL Server, SQLite, and of course any database for which a JDBC driver exists.
If you prefer, you can construct databases graphically using JDeveloper’s Database Diagram tool. It’s not unlike building a GUI by dragging and dropping buttons, scrollbars, and such onto a canvas. The idea is the same, only you’re dragging database objects -- tables, foreign keys, sequences, and relationships -- onto a database canvas.
JDeveloper also supports Oracle's "offline database" feature. This represents databases (and database objects) with XML-based definitions that let you work with database elements -- to create tables, modify table structure, drop tables, and so on -- without having to set up a live connection. You can do all of your management work without interfering with the ongoing operations of a live database. Once you have the setup you want, you reconcile the changes to the live database.