DO expr [, expr] ...
DO executes the expressions but
does not return any results. In most respects,
DO is shorthand for
, but has the
advantage that it is slightly faster when you do not care about
DO is useful primarily with
functions that have side effects, such as
pauses, but also produces a result set:
mysql> SELECT SLEEP(5); +----------+ | SLEEP(5) | +----------+ | 0 | +----------+ 1 row in set (5.02 sec)
DO, on the other hand, pauses
without producing a result set.:
mysql> DO SLEEP(5); Query OK, 0 rows affected (4.99 sec)
This could be useful, for example in a stored function or trigger, which prohibit statements that produce result sets.
DO only executes expressions. It
cannot be used in all cases where
SELECT can be
used. For example,
DO id FROM t1 is invalid
because it references a table.