Syntax:
DO expr [, expr] ...

DO executes the expressions but does not return any results. In most
respects, DO is shorthand for SELECT expr, ..., but has the advantage
that it is slightly faster when you do not care about the result.

DO is useful primarily with functions that have side effects, such as
RELEASE_LOCK().

URL: http://dev.mysql.com/doc/refman/5.5/en/do.html

