Erm... that\'s a very, very, very broad and ambitious question. Many flame wars have been fought over it but I\'ll do my best.
Relational database is a relatively complex piece of software so there\'s no dominant \"best of breed\" product in the open source DB arena. The major players, however, include:
- MySQL (biggest community, focus on performance & stability, somewhat lacking in enterprise features but that\'s changing rapidly)
- PostgreSQL (focus on feature completeness & standard support, performance catching up fast)
- Firebird (formerly a closed-source database released by Borland)
- there are rumours Computer Associates is about to open-source Ingres so that should stir things up a bit...
As for embeddable databases (i.e. something designed to be run on a box such as the Z):
- sqlite (used for storing PIM data in newest Opie versions)
- hsqldb (written in Java, used in Java apps, very straightforward)
- tinysql (don\'t know much about that but I think it\'s still maintained)
Out of all these, I ran mysql, hsqldb and sqlite on my 5500, no problems. hsqldb has a nice GUI client but, of course, you have to have Java set up.
As for comparisons vs. Oracle or MSSQL, you could write a thesis on that but the first three I\'ve mentioned are pretty much up there although Oracle Inc. and M$ would like you to think otherwise. The only major difference is perhaps admin tools (always more eye-candy in the proprietary land) and a few features mostly for Fortune 500 level databases. As soon as mysql gets true integrity constraints, stored procedures and nested queries (which PostgreSQL already has if I\'m correct) it will be a killer.
Apologies for everyone whose favorite DB I\'ve failed to mention, it\'s hard to keep up.
z.
