SQL Queries for Mere Mortals A Hands-On Guide to Data Manipulation in SQL

by Viescas, John L.; Hernandez, Michael J.

• ISBN13: 9780321444431
• ISBN10: 0321444434
• Edition: 2nd
• Format: Paperback
• Copyright: 2007-09-24
• Publisher: Addison-Wesley Professional

Summary

Unless you are working at a very advanced level, this is the only SQL book you will ever need. The authors have taken the mystery out of complex queries and explained principles and techniques with such clarity that a "Mere Mortal" will indeed be empowered to perform the superhuman. Do not walk past this book! --Graham Mandeno, Database Consultant SQL Queries for Mere Mortalsprovides a step-by-step, easy-to-read introduction to writing SQL queries. It includes hundreds of examples with detailed explanations. This book provides the tools you need to understand, modify, and create SQL queries --Keith W. Hare, Convenor, ISO/IEC JTC1 SC32 WG3--the International SQL Standards Committee I learned SQL primarily from the first edition of this book, and I am pleased to see a second edition of this book so that others can continue to benefit from its organized presentation of the language. Starting from how to design your tables so that SQL can be effective (a common problem for database beginners), and then continuing through the various aspects of SQL construction and capabilities, the reader can become a moderate expert upon completing the book and its samples. Learning how to convert a question in English into a meaningful SQL statement will greatly facilitate your mastery of the language. Numerous examples from real life will help you visualize how to use SQL to answer the questions about the data in your database. Just one of the "watch out for this trap" items will save you more than the cost of the book when you avoid that problem when writing your queries. I highly recommend this book if you want to tap the full potential of your database. --Kenneth D. Snell, Ph.D., Database Designer/Programmer I don't think they do this in public schools any more, and it is a shame, but do you remember in the seventh and eighth grades when you learned to diagram a sentence? Those of you who do may no longer remember how you did it, but all of you do write better sentences because of it. John Viescas and Mike Hernandez must have remembered because they take everyday English queries and literally translate them into SQL. This is an important book for all database designers. It takes the complexity of mathematical Set Theory and of First Order Predicate Logic, as outlined in E. F. Codd's original treatise on relational database design, and makes it easy for anyone to understand. If you want an elementary- through intermediate-level course on SQL, this is the one book that is a requirement, no matter how many others you buy. --Arvin Meyer, MCP, MVP Even in this day of wizards and code generators, successful database developers still require a sound knowledge of Structured Query Language (SQL, the standard language for communicating with most database systems). In this book, John and Mike do a marvelous job of making what's usually a dry and difficult subject come alive, presenting the material with humor in a logical manner, with plenty of relevant examples. I would say that this book should feature prominently in the collection on the bookshelf of all serious developers, except that I'm sure it'll get so much use that it won't spend much time on the shelf! -- Doug Steele, Microsoft Access Developer and author Over the last several decades, SQL has evolved from a language known only to computer specialists to a widely used international standard of the computer industry. The number of new applications deployed each year using SQL now totals in the millions. If you are accessing corporate information from the Internet or from an internal network, you are probably using SQL. This new edition ofSQL Queries for Mere Mortalshelps new users learn the foundations of SQL queries, a

Author Biography

John L. Viescas is an independent consultant with more than 40 years of experience. He began his career as a systems analyst, designing large database applications for IBM mainframe systems. He spent six years at Applied Data Research in Dallas, Texas, where he directed a staff of more than 30 people and was responsible for research, product development, and customer support of database products for IBM mainframe computers. While working at Applied Data Research, John completed a degree in business finance at the University of Texas at Dallas, graduating cum laude.

John joined Tandem Computers, Inc., in 1988, where he was responsible for the development and implementation of database marketing programs in Tandem's U.S. Western Sales region. He developed and delivered technical seminars on Tandem's relational database management system, NonStop SQL, in a geographic area spanning Hawaii to Colorado and Alaska to Arizona. John wrote his first book, A Quick Reference Guide to SQL (Microsoft Press, 1989), as a research project to document the similarities in the syntax among the ANSI-86 SQL standard, IBM's DB2, Microsoft's SQL Server, Oracle Corporation's Oracle, and Tandem's NonStop SQL. He wrote the first edition of Running Microsoft Access (Microsoft Press, 1992) while on sabbatical from Tandem. He has since written four editions of Running, two editions of Microsoft Office Access Inside Out (Microsoft Press, 2004 and 2007--the successor to the Running series), and Building Microsoft Access Applications (Microsoft Press, 2005).

John formed his own company in 1993. He provides information systems management consulting for a variety of small to large businesses around the world, with a specialty in the Microsoft Access and SQL Server database management products. He maintains offices in Nashua, New Hampshire, and Paris, France. He has been recognized as a "Most Valuable Professional" every year since 1993 by Microsoft Product Support Services for his assistance with technical questions on public support forums.

You can visit John's Web site at www.viescas.com.

Michael J. Hernandez is a veteran database developer with more than 20 years of experience developing applications for a wide variety of clients in diverse industries. Mike specializes in relational database design and is the author of the best-selling database design book Database Design for Mere Mortals, Second Edition (Addison-Wesley, 2004). He has worked with SQL throughout his career, developing applications using SQL-based databases such as Microsoft Access and Microsoft SQL Server. He has also been a contributing author and technical editor to various database-related books and periodicals.

Mike became a full-time employee at Microsoft in 2002. He initially was the Community Program Manager for the Visual Studio Tools for Office (VSTO) Team, leading and managing the team's developer community engagement efforts. In 2006, Mike became the Product Manager for VSTO, becoming responsible for helping to guide the strategic future of the product and promoting VSTO to customers and developers via a variety of venues. As he has done so often throughout his career, Mike often speaks at developer events, conferences, and user group meetings across the nation and around the world.

In a previous life, Mike had a career as a musician and performed for audiences far and wide. He attributes both his easygoing presentation style and his ability to connect with an audience to his days as a performer. Ever the musician, Mike formed a band from members of the VSTO team and gets to play his beloved guitar before new crowds and audiences. He still tinkers on his guitar quite a bit, stealing a few minutes here and there between meetings at work. Mike enjoys the little things in life, such as spending long hours at Barnes & Noble, sipping a tall Americano at Starbucks, puffing on a fine cigar, and riding his mountain bike along with his wife, Kendra.

Table of Contents

Foreword	p. xvii
Preface	p. xix
About the Authors	p. xxi
Introduction	p. xxiii
Are You a Mere Mortal?	p. xxiii
About This Book	p. xxiv
What This Book Is Not	p. xxv
How to Use This Book	p. xxvi
Reading the Diagrams Used in This Book	p. xxvii
Sample Databases Used in This Book	p. xxx
"Follow the Yellow Brick Road"	p. xxxii
Relational Databases and SQL	p. 1
What Is Relational?	p. 3
Topics Covered in This Chapter	p. 3
Types of Databases	p. 3
A Brief History of the Relational Model	p. 4
Anatomy of a Relational Database	p. 6
What's in It for You?	p. 15
Where Do You Go from Here?	p. 16
Summary	p. 17
Ensuring Your Database Structure Is Sound	p. 19
Topics Covered in This Chapter	p. 19
Why Is This Chapter Here?	p. 19
Why Worry about Sound Structures?	p. 20
Fine-Tuning Fields	p. 21
Fine-Tuning Tables	p. 30
Establishing Solid Relationships	p. 42
Is That All?	p. 50
Summary	p. 51
A Concise History of SQL	p. 53
Topics Covered in This Chapter	p. 53
The Origins of SQL	p. 54
Early Vendor Implementations	p. 55
". . . And Then There Was a Standard"	p. 56
Evolution of the ANSI/ISO Standard	p. 58
Commercial Implementations	p. 64
What the Future Holds	p. 65
Why Should You Learn SQL?	p. 65
Summary	p. 66
SQL Basics	p. 69
Creating a Simple Query	p. 71
Topics Covered in This Chapter	p. 71
Introducing SELECT	p. 72
The SELECT Statement	p. 73
A Quick Aside: Data versus Information	p. 75
Translating Your Request into SQL	p. 77
Eliminating Duplicate Rows	p. 84
Sorting Information	p. 87
Saving Your Work	p. 92
Sample Statements	p. 93
Summary	p. 102
Problems for You to Solve	p. 103
Getting More Than Simple Columns	p. 105
Topics Covered in This Chapter	p. 105
What Is an Expression?	p. 106
What Type of Data Are You Trying to Express?	p. 107
Changing Data Types: The CAST Function	p. 110
Specifying Explicit Values	p. 112
Types of Expressions	p. 117
Using Expressions in a SELECT Clause	p. 128
That "Nothing" Value: Null	p. 135
Sample Statements	p. 139
Summary	p. 147
Problems for You to Solve	p. 149
Filtering Your Data	p. 151
Topics Covered in This Chapter	p. 151
Refining What You See Using WHERE	p. 151
Defining Search Conditions	p. 156
Using Multiple Conditions	p. 178
Nulls Revisited: A Cautionary Note	p. 193
Expressing Conditions in Different Ways	p. 197
Sample Statements	p. 198
Summary	p. 206
Problems for You to Solve	p. 207
Working with Multiple Tables	p. 211
Thinking in Sets	p. 213
Topics Covered in This Chapter	p. 213
What Is a Set, Anyway?	p. 214
Operations on Sets	p. 215
Intersection	p. 216
Difference	p. 222
Union	p. 228
SQL Set Operations	p. 233
Summary	p. 242
Inner Joins	p. 243
Topics Covered in This Chapter	p. 243
What Is a JOIN?	p. 243
The Inner Join	p. 244
Uses for Inner Joins	p. 262
Sample Statements	p. 263
Summary	p. 288
Problems for You to Solve	p. 289
Outer Joins	p. 293
Topics Covered in This Chapter	p. 293
What Is an Outer Join?	p. 293
The Left/Right Outer Join	p. 295
The Full Outer Join	p. 314
Uses for Outer Joins	p. 318
Sample Statements	p. 319
Summary	p. 335
Problems for You to Solve	p. 335
Unions	p. 339
Topics Covered in This Chapter	p. 339
What Is a Union?	p. 339
Writing Requests with Union	p. 342
Uses for Union	p. 352
Sample Statements	p. 353
Summary	p. 365
Problems for You to Solve	p. 366
Subqueries	p. 369
Topics Covered in This Chapter	p. 369
What Is a Subquery?	p. 370
Subqueries as Column Expressions	p. 372
Subqueries as Filters	p. 377
Uses for Subqueries	p. 392
Sample Statements 394 Summary	p. 409
Problems for You to Solve	p. 410
Summarizing and Grouping Data	p. 413
Simple Totals	p. 415
Topics Cover
Table of Contents provided by Publisher. All Rights Reserved.

Excerpts

"Language is by its very nature a communal thing; that is, it expresses never the exact thing but a compromise that which is common to you, me, and everybody." Thomas Earnest Hulme,Speculations Learning how to retrieve information from or manipulate information in a database is commonly a perplexing exercise. However, it can be a relatively easy task as long as you understand the question you're asking or the change you're trying to make to the database. After you understand the problem, you can translate it into the language used by any database system, which in most cases is Structured Query Language (SQL). You have to translate your request into an SQL statement so that your database system knows what information you want to retrieve or change. SQL provides the means for you and your database system to communicate. Throughout our many years as database consultants, we've found that the number of people who merely need to retrieve information from a database or perform simple data modifications in a database far outnumber those who are charged with the task of creating programs and applications for a database. Unfortunately, no books focus solely on this subject, particularly from a "mere mortals" viewpoint. There are numerous good books on SQL, to be sure, but most are targeted to database programming and development. With this in mind, we decided it was time to write a book that would help people learn how to query a database properly and effectively. We produced the first edition of this book in 2000. With this new edition, we also wanted to introduce you to the basic ways to change data in your database using SQL. The result of our decision is in your hands. This book is unique among SQL books in that it focuses on SQL with little regard to any one specific database system implementation. This second edition includes hundreds of new examples, and we included versions of the sample databases using the popular open-source MySQL database system. When you finish reading this book, you'll have the skills you need to retrieve or modify any information you require.