ComputerWorld has posted three SQL puzzles that were written by Joe Celko on their website. These puzzles come from Joe Celko's latest book Joe Celko's SQL Puzzles and Answers, Second Edition
These are the puzzles:
Puzzle 1: FISCAL YEAR TABLES
Puzzle 4: SECURITY BADGES
Puzzle 9: AVAILABLE SEATS
the site has individual links to each puzzle and answer, the link to the puzzles is here: http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9012350&source=NLT_APP&nlid=48
Let me know what you think and if you can come up with better/different answers.