Sams Teach Yourself SQL in 10 Minutes, Fourth Edition

Lesson 16. Updating and Deleting Data

In this lesson, you will learn how to use the UPDATE and DELETE statements to enable you to further manipulate your table data.

Updating Data

To update (modify) data in a table the UPDATE statement is used. UPDATE can be used in two ways:

• To update specific rows in a table

• To update all rows in a table

You’ll now take a look at each of these uses.

Caution: Don’t Omit the WHERE Clause

Special care must be exercised when using UPDATE, because it is all too easy to mistakenly update every row in your table. Please read this entire section on UPDATE before using this statement.

Tip: UPDATE and Security

Use of the UPDATE statement might require special security privileges in client-server DBMSs. Before ...