This book will teach you the 80% of SQL you probably need to use it effectively, and will mix in concepts in data modeling at the same time. If you’ve been fumbling around building web, desktop, or mobile applications because you don’t know SQL, then this book is for you. It is written for people with no prior database, programming, or SQL knowledge, but knowing at least one programming language will help.
Learn SQL The Hard Way. It’s only in Alpha though, so I wouldn’t rush out and start working through it, unless you want to file bug reports.