Ok, I had to add one more thing while trying to migrate databases.
READ THIS ! If your .sql file is less than about 3meg in size, you will probably be fine with either method.
If your .sql file is larger, you can try the upload but you may get timeout errors. This is NOT the fault of WordPress – it is a host setting. If you have your own server you can change the settings. If you cannot alter that, and you get timeouts, you will have to do the following; (etc., etc…)
My idiotprogrammer database for this weblog is 93 Megabytes, which I had to open up in a text file (imagine that: a 93 MB textfile!). 9/10 of it looks like useless crap. Somehow I need to shrink/delete this sql file. I have a feeling that this migration might be more complicated than originally expected 🙂
Update: It might not be that hard. Half of the database is actual content; the other half is remnants of a logging program I installed a year ago and then disabled. Still, that’s over 45 mb of content. Wow.
Update #2 This wasn’t so hard after all. Apparently instead of mass deleting spam comments, I had been simply been marking them as spam. So I merely needed to run a command, Delete * from wpcomments where status=”spam” or something like that. Also, I ended up deleting the statraq plugins entirely. That turned my db into a more manageable 4 mb.