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Sams Teach Yourself SQL in 24 Hours, Fifth Edition by Arie D. Jones, Ron D. Plew, Ryan Stephens

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Hour 16. Using Indexes to Improve Performance

What You’ll Learn in This Hour:

How indexes work

How to create an index

The different types of indexes

When to use indexes

When not to use indexes

In this hour, you learn how to improve SQL statement performance by creating and using indexes. You begin with the CREATE INDEX command and learn how to use indexes that have been created on tables.

What Is an Index?

Simply put, an index is a pointer to data in a table. An index in a database is similar to an index in the back of a book. For example, if you want to reference all pages in a book that discuss a certain topic, you first refer to the index, which lists all topics alphabetically, and it refers you to one or more specific page numbers. ...

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