The Language of SQL- P3 pot

Correlated Subquery Updates 181 Looking Ahead 183 Chapter 18 Maintaining Tables 185 Data Definition Language . . 185 Table Attributes 186 Table Columns. 187 Primary Keys and Indexes. . . 188 Foreign Keys . . 189 Creating Tables 190 Creating Indexes 192 Looking Ahead 192 Chapter 19 Principles of Database Design 195 Goals of Normalization 196 How to Normalize Data 198 The Art of Database Design. 202 Alternatives to Normalization 203 Looking Ahead 205 Chapter 20 Strategies for Displaying Data 207 Beyond SQL . . . 207 Reporting Tools and Crosstab Reports. . . 208 Spreadsheets and Pivot Tables 210 Looking Ahead 212 Appendix A Getting Started with Microsoft SQL Server 215 Overview 215 Installing SQL Server Express 2008 215 Installing SQL Server Management Studio 216 Using SQL Server Management Studio . . 217 Appendix B Getting Started with MySQL 219 Overview 219 Installing MySQL Community Server 220 Installing MySQL Workbench 221 Using MySQL Workbench . . 222 Contentsx Appendix C Getting Started with Oracle 225 Overview 225 Installing Oracle Database Express Edition . 225 Using Oracle Database Express Edition 227 Appendix D Listing of All SQL Statements 229 Index 231 Contents xi Introduction Research has shown that, being pressed for time, most readers tend to skip the introduction of any book they happen to read and then proceed immediately to the first real chapter. With that fact firmly in mind, we will only cover relatively unimportant material in the introduction, such as an explanation of what you will and will not learn by reading this book. On second thought, perhaps the introduction really is relevant, so you might as well stick with it. We’ll make it brief. Even if you’re not yet familiar with SQL, suffice it to say that it is a complex language with many components and features. In this book, we’re going to focus on one main topic: ■ How to use SQL to retrieve data from a database To a lesser extent, we will also cover: ■ How to update data in a database ■ How to build and maintain databases ■ How to design relational databases ■ Strategies for displaying data after it has been retrieved xii A number of features make this book unique among introductory SQL books: ■ You will not be required to download software or sit with a computer as you read the text. Our intent is to provide examples of SQL usage that can be understood simply by reading the book. The text includes small data samples that will allow you to see clearly how SQL statements work. ■ A language-based approach is employed to enabl e you to learn SQL as you would learn English. Topics are organized in an intuitive and logical sequence. SQL keywords are introduced one at a time, allowing you to build on your prior under- standing as you encounter new words and concepts. ■ This book covers the syntax of three widely used databases: Microsoft SQL Server, MySQL, and Oracle. If there are any differences between the three databases, the Microsoft SQL Server syntax is shown in the main text. Special ‘‘Database Differences’’ boxes show and explain any variations in the syntax for MySQL or Oracle. ■ An emphasis is given to relevant aspects of SQL for retrieving data. This approach is useful for those who only need to use SQL in conjunction with a reporting tool. Additionally, a final chapter is provided that covers strategies for displaying data after it has been retrieved, including ideas on how to use crosstab reports and pivot tables. Finally, one additional question that we’ll address in the introduction: How is SQL pronounced? There are actually two choices. One option is to simply say it as individual letters, like ‘‘S-Q-L.’’ Another possibility is to pronounce it as ‘‘sequel.’’ There are peo- ple who claim that only one of the two pronunciations is correct, but there is no real agreement on the question. It’s basically a matter of personal preference. As for what the letters S-Q-L mean, most agree that they stand for ‘‘structured query language.’’ However, there are a few people who will argue that SQL stands Introduction xiii for nothing at all since the language is derived from an old language from IBM called sequel, which did not stand for structured query language. At any rate, the introduction is done. And now . . . on to some real information. Companion Web Site Downloads Please see Appendix D, for a description of the files available on the companion Web site. These files list all SQL statements and provide all data shown in the book. You may download the companion Web site files from www.courseptr.com/ downloads. Introductionxiv . covers the syntax of three widely used databases: Microsoft SQL Server, MySQL, and Oracle. If there are any differences between the three databases, the Microsoft SQL Server syntax is shown in the. ‘‘sequel.’’ There are peo- ple who claim that only one of the two pronunciations is correct, but there is no real agreement on the question. It’s basically a matter of personal preference. As for what the. that they stand for ‘‘structured query language. ’’ However, there are a few people who will argue that SQL stands Introduction xiii for nothing at all since the language is derived from an old language