DO Statement 

DO expr [, expr] ...

DO语句执行表达式但不返回任何结果。

mysql> SELECT SLEEP(5);
+----------+
| SLEEP(5) |
+----------+
|        0 |
+----------+
1 row in set (5.02 sec)
mysql> DO SLEEP(5);
Query OK, 0 rows affected (4.99 sec)

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.

posted @ 2020-08-17 06:39  wongchaofan  阅读(108)  评论(0)  编辑  收藏  举报