DOexpr[,expr] ...

DOexecutes the expressions but does not return any results. In most respects,DOis shorthand forSELECTexpr, ..., but has the advantage that it is slightly faster when you do not care about the result.

DOis useful primarily with functions that have side effects, such asRELEASE_LOCK().

Example: ThisSELECTstatement 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.

DOonly executes expressions. It cannot be used in all cases whereSELECT可以使用。例如,DO id FROM t1is invalid because it references a table.