Using SQL

It's old but a super value for the price. Back around 1992, while working in Database Systems at Digital, I was assigned the task of evaluating most of the commmercially published SQL books on the market. The purpose was to choose a book to distribute with each license of a new relational database product that was eventually cancelled. I found Groff and Weinberg to be the best by far in terms of literary and technical quality. It preceded the SQL92 standard but I still have a copy on my shelf today and refer to it when I need a refresher on correlated subqueries or something of that nature.