Chapter 20. Updating and Deleting Data

In this chapter, 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

Let’s take a look at each of these uses.


Don’t Omit the WHERE ClauseSpecial 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.


UPDATE and SecurityUse of the UPDATE statement can be restricted and controlled. More on this in Chapter 28, “Managing Security.”


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