Beginning SQL, Looking for Useful, Simple Applications

Hello all!

I am the resident Tessitura human for most things here at Mystic, and I'm starting to teach myself bits of SQL. I've figured out how to set batches to 'held', or 'closed', I can track down orders using the Transaction Number, and so forth- very basic, but useful, as we've had to use those from time to time.

What are some useful, and simple, things I can do with some basic commands?

Also, what would be good resources to building my skills in that area? I've pulled up some past powerpoint presentations done by Tessitura folks, and those have been helpful. Any other ideas?