MySQL - is the most popular open source database. Its speed, scalability and reliability make it the right choice for corporate IT departments, Web developers and packaged software vendors.
Drizzle - "a lightweight SQL database for cloud and web". This project is about building a database designed for the typical web usage patterns for a database. It is being designed for massive concurrency on modern multi-cpu/core architecture. The code is originally derived from MySQL.
PostgreSQL - is a sophisticated Object-Relational DBMS, supporting almost all SQL constructs, including subselects, transactions, and user-defined types and functions.
phpMyAdmin - is intended to handle the adminstration of MySQL over the web.
SQLite - is a small C library that implements a self- contained, embeddable, zero-configuration SQL database engine.
GtkSQL - is a graphical front-end for PostgreSQL, MySQL and SQLite. It provides an easy interface to write and run SQL queries.
SAP MaxDB - is the database management system developed and supported by SAP AG. It has its focus on the requirements of SAP customers and SAP applications and can be used as a less expensive alternative to databases from other vendors for your own or third-party applications as well. SAP MaxDB is available for the most prominent operating system/hardware platforms Microsoft Windows, Linux, and Unix.
Oracle Database - Simplifying everything from installation to tuning and troubleshooting to backup and recovery, the new release is packed with features designed to make the DBA's job easier, either by completely automating tasks or by transferring control of important functions to the server.
SAP DB - "The FREE Enterprise Open Source Database".
YARD - "The powerful easy to use SQL database".
InterBase SMP - combines a multi-generational architecture with simple installation, low administration and deployment costs, automatic crash recovery, and a self-tuning engine that makes it well-suited for small enterprise, desktop, and embedded applications.
Firebird - is a relational database offering many ANSI SQL-92 features. Firebird offers excellent concurrency, high performance, and powerful language support for stored procedures and triggers.
DB2 - is the next-generation hybrid data server with optimized management of both XML and relational data.
Apache Derby - is a full-featured, open source relational database management system (RDBMS) that is based on Java and SQL.
dbMetrix - "is a copy-lefted, open-sourced SQL database tool. My goal is to write a very graphical, clean, consistent, modularized front end to various (currently opensourced) SQL servers".
ODBC - is an open specification for providing application developers with a predictable API with which to access Data Sources. Data Sources include SQL Servers and any Data Source with an ODBC Driver.
EMS MySQL Utils - are powerful data management utilities for MySQL Server, which make your work with the server much easier and faster.
Qddb - is an acronym for "Quick and Dirty DataBase", largely due to its origin. Qddb was originally to be a quickly implemented efficient database tool. Qddb is freely available under the GNU General Public License.
Sybase ASE - Adaptive Server Enterprise for Linux is a highly scalable, high-performance database engine that includes standard features of Adaptive Server Enterprise and all related connectivity components.
Rekall - is a personal, programmable DBMS system in the style of Paradox or MS Access. The system will be integrated into KOffice as a standard version, and "pro" plug ins will be available for sale from theKompany.com.
MDB Tools project - is an effort to document the MDB file format used in MS Access database package, and to provide a set of tools and applications to make that data available on other platforms.
knoda - "Knorr's Datenbank" is a database frontend for KDE. It is based on hk_classes and is released under the GPL. Its driver concept allows a uniform connection to different database servers (Dbase/Xbase, MS Access/Mdbtools, Mysql , Postgresql , SQLite or ODBC).