Sams Teach Yourself SQL in 10 Minutes, Second Edition

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.

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.

UPDATE and Security Use of the UPDATE statement might require special security privileges in client-server DBMS'. ...