The Fourth Edition

The Practical SQL Handbook, fourth edition, continues to focus on industry-practice SQL, but the information included is at once more general and more specific than earlier editions. For the fourth edition, we had two objectives:

• To expand our test base, running the examples on five different database systems

• To show vendor-specific differences among systems

Test on More Systems

For the fourth edition, all examples were run on five systems (Sybase Adaptive Server Anywhere, Adaptive Server Enterprise, Microsoft SQL Server, Oracle, Informix), rather than on Sybase systems only, as in the third edition. This expanded test base makes the information more universal. We are no longer limited to what we can explore or verify on a particular system. If an important feature doesn't exist on Adaptive Server Anywhere (ASA, the RDBMS included on the CD), we can show code and results from Oracle or SQL Server.

Show Examples of Vendor-Specific Differences

On the other hand, this edition is more specific. It includes information on specific idiosyncrasies of the five SQL dialects, warning readers where to look for differences. In this, it reflects the real world—lots of database users are working with multiple systems, either sequentially or simultaneously. Interesting SQL differences are flagged as SQL Variants, in-text sections that show details of differences in SQL use by different vendors. For example, how single and double quotes are used, or database users added, or outer joins specified. You won't see code for every one of the five systems every time, but you'll get an introduction to the kind of differences that are likely in a particular area.