Why New Editions? Many things have changed since this book was first published in 1989, and SQL is no exception. The SQL language has expanded tremendously, both in numbers of users and in numbers of commands. Sales of relational databases continue to at a strong and steady rate. When we wrote the first edition of The Practical SQL Handbook, the American National Standards Institute (ANSI) had already approved the 1986 SQL standard. The International Standards Organization (ISO) adopted it in 1987. Both ANSI and ISO helped create the 1989 version. The 1986 standards were skimpy, lacking features that most commercial vendors offered. The 1989 standards were more complete, but still left many important elements undefined. For the first edition, we felt we should focus on industry practice: as always, each vendor keeps a wary eye on what the others are doing and makes core offerings similar enough to attract both customers migrating from competitors, as well as new users looking for database systems they can build on. Because of this, we left both the not-quite-jelled ANSI standards and particular vendor implementations to the experts in those fields and concentrated on the common ground: generic or "industry-practice" SQL. Our goal was to offer the intelligent amateur practical information on how to use the actually available SQL of that time. The 1992 ANSI standard (often called SQL-2 or SQL-92) represented a new stage in SQL development. This standard was more comprehensive than the 1989 standard: in written form it contained more than four times as many pages as the earlier version. Database vendors have adopted large parts of the 1992 standard. With the widespread adoption of the SQL-92 standard, the industry practice and the ANSI/ISO standards began to converge.
Despite vendor-specific differences, there is a general, industry-wide core of SQL commands that all users need to understand. Adopting standards doesn't happen overnight; it is a long process. At any point, vendors will have varying levels of conformance and will continue to produce vendor-specific variations. This book aims to give SQL users a mastery of the fundamentals of the language, with a side glance at the specifics of particular implementations.
Changes for Recent Editions The changes for recent editions have been in three areas: to include more real-world examples to emphasize the SQL-92 features that most vendors have implemented to provide software for hands-on practice.
More Real-World Examples In talking to new and developing SQL users, we heard over and over of their need for more examples to follow, change, narrow, and broaden. Accordingly, the bulk of the added material in the second edition consisted of code "recipes." Chapter 11, "Solving Business Problems," is a selection of code samples based on questions and answers that came over popular computer newsgroups. We reproduce interesting problems and solutions in terms of the sample bookbiz database used throughout the book. The chapter includes examples of using the CASE function for conditional logic, formatting results, and finding date data. A few samples fall into a different category. They aren't so much solutions to problems as indications of common errors. They include issues with DISTINCT and misunderstandings of what SQL can do.
Emphasize SQL-92 With the third edition, we revised the book to incorporate the SQL-92 features that most vendors have adopted. These include new datatypes, additions to the CREATE TABLE statement that allow built-in integrity constraints, modifications to the ORDER BY and GROUP BY clauses, the new escape character for the LIKE keyword, and changes to GRANT and REVOKE, among others.
Provide Software for Hands-On Practice With the fully-usable trial version of Sybase's Adaptive Server Anywhere on the CD that accompanies this book, you can run the examples (and your variants) on a PC. We've always felt that the secret to learning SQL is practice. Now you can experiment to your heart's content, trying out code samples with data you know and checking the results to see if they are what you expect. When you're stumped by complicated code, break it into small, meaningful pieces and run them separately to make sure you understand what each segment does. Then put them together in increasingly complex combinations--and have fun! The Sybase Adaptive Server Anywhere software on the CD is a 60-day full-feature version that allows you to create objects as well as query existing ones. ASA is built with an updated version of the bookbiz database: for the fourth edition, we increased book prices and made dates more recent. Also included on the CD are scripts to create the database on ASA (in case you damage the original) and on the other systems discussed in the book.
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 include examples showing vendor-specific differences among systems
Test on More Systems For the fourth edition, all examples were run on five systems (Sybase Adaptive Server Anywhere and 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 on how single and double quotes are used by different vendors, or 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.
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This latest edition of the best-selling implementation guide to the Structured Query Language teaches SQL fundamentals while providing practical solutions for critical business applications. The Practical SQL Handbook, Fourth Edition now includes expanded platform SQL coverage and extensive real-world examples based on feedback from actual SQL users.
The Practical SQL Handbook begins with a step-by-step introduction to SQL basics and examines the issues involved in designing SQL-based database applications. It fully explores SQL’s most popular implementations from industry leaders, Oracle, Microsoft, Sybase, and Informix.
Highlights include:
- Detailed coverage of SQL commands for creating databases, tables, and indexes, and for
- adding, changing, and deleting data
- Using the SELECT command to retrieve specific data
- Handling NULL values (missing information) in a relational database
- Joining tables, including self joins and outer joins (ANSI and WHERE-clause syntax)
- Working with nested queries (subqueries) to get data from multiple tables
- Creating views (virtual tables) to provide customized access to data
- Using SQL functions
A bonus CD-ROM contains a time-limited, full-feature version of the Sybase® Adaptive Server Anywhere™ software as well as the sample database, scripts, and examples included in the book.
The Practical SQL Handbook is the most complete reference available for day-to-day SQL implementations.
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