Linux supports many styles of databases, ranging from simple text files (/etc/passwd) to low level B-Tree databases (Berkely DB and bdb), lightweight SQL (sqlite), and fully featured relational database servers, such as Postgres, Oracle, and MySQL.
One rule of thumb for selecting a database style is to use the least complex system that works for your application. A text file and grep is sufficient for a small database when the fields are known and fixed.
Some applications require references. For example, a database of books and authors should be created with two tables, one for books and one for the authors, to avoid duplicating the author information for each book.
If the table is read more often than it's modified, then SQLite is a good choice. This database engine does not require a server, which makes it portable and easy to embed in another application (as Firefox does).
If the...
