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
  • Hour 3. Managing Database Objects
    • What Are Database Objects?
    • What Is a Schema?
    • A Table: The Primary Storage for Data
    • Integrity Constraints
    • Summary
    • Q&A
    • Workshop
  • 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

Q&A

1. When I name a table that I am creating, is it necessary to use a suffix such as _TBL ?

   Absolutely not. You do not have to use anything. For example, a table to hold employee information could be named similar to the following, or anything else that would refer to what type of data is to be stored in that particular table:

   EMPLOYEE 
   
   EMP_TBL
   
   EMPLOYEE_TBL
   
   EMPLOYEE_TABLE
   
   WORKER
   

2. Why is it so important to use the schema name when dropping a table?

   Here's a true story about a new DBA that dropped a table: A programmer had created a table under his schema with the same name as a production table. That particular programmer left the company. The programmer's database account was being deleted from the database, but the DROP USER statement returned an error due to the fact that outstanding objects were owned by the programmer. After some investigation it was determined that the programmer's table was not needed, so a DROP TABLE statement was issued.

   It worked like a charm—but the problem was that the DBA was logged in as the production schema when the DROP TABLE statement was issued. The DBA should have specified a schema name, or owner, for the table to be dropped. Yes, the wrong table in the wrong schema was dropped. It took approximately eight hours to restore the production database.

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