I'm sure there is a way to do it, but it's not a simple query which is probably why no one has come and posted it. And since, the field isn't empty, that makes it a bit more difficult because you can't just say WHERE joindate=''. You need to find something unique about the users that need their joindates changed. What is in the joindate field exactly - is it exactly the same for all the users you want to change? (It's gonna be in unixtime.) Also, what is a user has never posted - what do you put in that field then?