I've had to do similar things a few times. The easiest approach for me has been to write a script that pulls from one data source and produces an output for the new data source. Just do a SELECT *
query for each table in your current database, and then dump all the rows into an INSERT INTO
query for your new database. You can either dump this into a file or pipe it straight into the database frontend.
It's not pretty, but honestly, pretty hardly seems to be a major concern for things like this. This technique is quick to write, and it works. Those are my primary criteria for things like this.
You might want to check out this thread, too. It looks like a couple of people have already put together basically what you need. I didn't look that far into it, though, so no guarantees.