i too recomend SQLite, a complete (SQL92 compliant) database stored in a single disk file. i use it in projects where a full RDBMS server would be overkill (i.e. most of my work :) and network acces to the DB is not required.

SQLite was the first RDBMS i used and my first introduction to SQL. i'd say it is relatively easy to learn. you definetly want to use version 3 with the excellent Perl module DBD::SQLite.

your first concern might be the integrity of data. i didn't have any problems with that using SQLite, but you might want to read about how SQLite3 takes care of this problem.

:)))))