On: 20 tips for MySQL db architects

[ars]

Small note about using unsigned ints: In PHP (and possibly others) they will turn into signed ints when you read them.

If you read and write them and never show them, it's probably OK, but if you have logic that checks for < 0, or the like, be aware of it.

But then again, if you have so many rows in a table that your auto_number has reached over 2 billion, you probably have other issues as well.