The Sams book (Douglas & Douglas, PostgreSQL: The comprehensive guide to building, programming, and administering PostgreSQL databases, 2nd ed) is very good. I wrote a little comment about it earlier in this group. My only complaint is that there isn't any information on rules. For basic database information, "Database Design for Mere Mortals, 2nd ed." is a good book that is commonly recommended. For SQL, I find the chapters in the PostgreSQL manual to be pretty good. For books, there is Wilton and Colby "Beginning SQL", SQL for Dummies, Teach Yourself SQL in 21 Days and Teach Yourself SQL in 24 Hours.
Michael Schmidt