Sams Teach Yourself SQL in 24 Hours

By Ron Plew and Ryan Stephens

• Table of Contents
  • Copyright
  • About the Authors
  • Acknowledgments
  • Tell Us What You Think!
  • Introduction
  • Part I: A SQL Concepts Overview
  • Hour 1. Welcome to the World of SQL
  • Part II: Building Your Database
  • Hour 2. Defining Data Structures
    • What Is Data?
    • Basic Data Types
    • Summary
    • Q&A
    • Workshop
  • Hour 3. Managing Database Objects
  • Hour 4. The Normalization Process
  • Hour 5. Manipulating Data
  • Hour 6. Managing Database Transactions
  • Part III: Getting Effective Results from Queries
  • Hour 7. Introduction to the Database Query
  • Hour 8. Using Operators to Categorize Data
  • Hour 9. Summarizing Data Results from a Query
  • Hour 10. Sorting and Grouping Data
  • Hour 11. Restructuring the Appearance of Data
  • Hour 12. Understanding Dates and Times
  • Part IV: Building Sophisticated Database Queries
  • Hour 13. Joining Tables in Queries
  • Hour 14. Using Subqueries to Define Unknown Data
  • Hour 15. Combining Multiple Queries into One
  • Part V: SQL Performance Tuning
  • Hour 16. Using Indexes to Improve Performance
  • Hour 17. Improving Database Performance
  • Part VI: Using SQL to Manage Users and Security
  • Hour 18. Managing Database Users
  • Hour 19. Managing Database Security
  • Part VII: Summarized Data Structures
  • Hour 20. Creating and Using Views and Synonyms
  • Hour 21. Working with the System Catalog
  • Part VIII: Applying SQL Fundamentals in Today's World
  • Hour 22. Advanced SQL Topics
  • Hour 23. Extending SQL to the Enterprise, the Internet, and the Intranet
  • Hour 24. Extensions to Standard SQL
  • Part IX: Appendixes
  • Appendix A. Common SQL Commands
  • Appendix B. Using MySQL for Exercises
  • Appendix C. Answers to Quizzes and Exercises
  • Appendix D. CREATE TABLE Statements for Book Examples
  • Appendix E. INSERT Statements for Data in Book Examples
  • Appendix F. Glossary
  • Appendix G. Bonus Exercises

What Is Data?

Data is a collection of information stored in a database as one of several different data types. Data includes names, numbers, dollar amounts, text, graphics, decimals, figures, calculations, summarization, and just about anything else you can possibly imagine. Data can be stored in uppercase, lowercase, or mixed case. Data can be manipulated or changed; most data does not remain static for its lifetime.

Data types are used to provide rules for data for particular columns. A data type deals with the way values are stored in a column as far as the length allocated for a column and whether values such as alphanumeric, numeric, and date and time data are allowed. There is a data type for every possible bit or combination of data that can be stored in a particular database. These data types are used to store data such as characters, numbers, dates and time, images, and other binary data. More specifically, the data might consist of names, descriptions, numbers, calculations, images, image descriptions, documents, and so forth.

The data is the purpose of any database and must be protected. The protector of the data is normally the database administrator (DBA), although it is every database user's responsibility to ensure that measures are taken to protect data. Data security is discussed in depth in Hour 18, "Managing Database Users," and Hour 19, "Managing Database Security."

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