When UPDATE doesn't work..

[rowew]

eg

UPDATE MyTable SET SomeField = 20 WHERE AnotherField = -1

If the table MyTable has no row with AnotherField = -1, obviously no update will take place, and the query will end normally. Is there any way to capture the fact that no update has taken place (other than the obvious trick of determining prior to the update whether AnotherField = -1 exists)? Is the number of changed rows stored anywhere? It is displayed when the update is performed in the MySQL command line interface.