Thank you all for your advice.

I will investigate the CSV option. Currently, the script reads and writes CSV files and does it pretty well. This has been an excellent option since (as it was pointed out) it requires nothing from the Web server. However, people now want to be able to use their databases.

Of course it would be cleaner to have one way of doing things rather than a CSV way and a DBI way. Unfortunately, performance will dictate whether or not I replace the current machinery for reading and writing CSV files.

Thank you also for recommending some databases. However, other than CSV, I am not planning to implement any particular database but instead a framework where people can configure my script to make use of whatever database they have installed on their Web server. I think DBI will be very good at this.

I'm proceeding with DBI and will sort out the installation issues for DBI and the various database drivers. I will be finding out if it's better to include lots of drivers with my program or have webmasters download and install drivers themselves, avoiding any possible licensing problems.

Thanks again,

Richard