Sams Teach Yourself SQL in 24 Hours, Second Edition

Updating Existing Data

Pre-existing data in a table can be modified using the UPDATE command. The UPDATE command does not add new records to a table, nor does it remove records—it simply updates existing data. The update is generally used to update one table at a time in a database, but can be used to update multiple columns of a table at the same time. An individual row of data in a table can be updated, or numerous rows of data can be updated in a single statement, depending on what's needed.

Updating the Value of a Single Column

The most simple form of the UPDATE statement is its use to update a single column in a table. Either a single row of data or numerous records can be updated when updating a single column in a table.

The syntax for ...