Book review: "Simply SQL" by Rudy Limeback

Rudy Limeback's "Simply SQL" (Sitepoint) is an overview of SQL targeted at web application developers, and intended to fill a gap between the basic "SQL 101"-type tutorials (seemingly compulsory in just about every introductory article or book about web programming) and more advanced texts covering topics which at first glance don't seem so relevant to the straightforward day-to-day requirements of many web applications.

The chapters are grouped into two main sections. The first deals with the details of the SQL language and comprises the bulk of the book. It starts with a short introduction to the SQL commands most commonly needed by web developers to create and modify data within the database (all the usual suspects - CREATE, ALTER, INSERT, UPDATE, DELETE and so on - are quickly dealt with here). The rest of this section focuses on the SELECT command (the one used to retrieve information), with each chapter covering one specific clause - FROM, WHERE, GROUP BY and so on - in quite extensive detail, and illustrated with examples from sample applications.

The second section of the book has three chapters covering some basic database design concepts, specifically SQL data types, relational integrity, and the use of "special structures" (such as tables that refer to themselves) for particular situations. The appendices then outline the basics of using some specific SQL implementations, along with details of the sample applications and scripts used in the main part of the book.

The heavy emphasis on the SELECT statement might seem odd, but it makes a lot of sense in the context of web applications where data is typically read from the database far more than it's written. The detailed examples are also excellent - at times invaluable - for clarifying things like (for example) the nuances of the different types of JOINS, the subtleties of the GROUP BY and HAVING clauses (useful for aggregating data from subsets of rows in conjunction with summing and averaging functions), and the issues with working with time data. I certainly learnt a few things - the GROUP BY clause was completely new to me, as were the distinctions between the FLOAT and DECIMAL data types (DECIMALs are exact - within certain limits - while FLOATs are approximate). I found the brief sections on views, derived tables and subqueries extremely enlightening, as was the discussion of foreign keys in the chapter on relational integrity, and the clear writing style throughout made the book a pleasure to read.

It's important to note that "Simply SQL" is based on the SQL standard, rather than the syntax of specific implementations (although in places it does indicate where there are notable deviations from the standard, particularly for MySQL) - also it doesn't cover any of the programming APIs, so it's not really a reference text (admittedly it doesn't claim to be). However with its clear and detailed explanations it looks like it would be a useful companion to more traditional reference or cookbooks and will definitely reward re-reading - least ways, I'm sure I'll be squeezing plenty more juice out of it in the future. So overall highly recommended.