SLEEP()

Description

Sleeps (pauses) for the number of seconds given by the duration argument, then returns 0.

Syntax

1. >
2. SLEEP(duration)

Arguments

Returned Value

• When sleep returns normally (without interruption), it returns 0.
• When SLEEP() returns 1 (with interruption or time out), the query returns no error.

For example:

1. In session 1, execute the following command to query the current connection_id and execute the SLEEP() function:

   1. mysql> select connection_id(); 2. +-----------------+ 3. | connection_id() | 4. +-----------------+ 5. | 1476 | 6. +-----------------+ 7. 1 row in set (0.03 sec) 8. mysql> select sleep(200); 2. At this point, open a new session, interrupt session 1, and run the following command.

   1. mysql> kill 1463; 2. Query OK, 0 rows affected (0.00 sec) 3. Check the query result of session 1:

   1. mysql> select sleep(200); 2. +------------+ 3. | sleep(200) | 4. +------------+ 5. | 1 | 6. +------------+ 7. 1 row in set (26.50 sec) - When SLEEP() returns an error (part of a query is uninterrupted). For example:

1. mysql> SELECT 1 FROM t1 WHERE SLEEP(1000); 2. ERROR 20101 (HY000): internal error: pipeline closed unexpectedly

Examples

1. -- without interruption
2. mysql> SELECT SLEEP(1);
3. +----------+
4. | sleep(1) |
5. +----------+
6. |        0 |
7. +----------+
8. 1 row in set (1.01 sec)

10. -- without interruption
11. mysql> SELECT SLEEP(1000);
12. +-------------+
13. | sleep(1000) |
14. +-------------+
15. |           0 |
16. +-------------+
17. 1 row in set (18 min 20.87 sec)

19. create table t1 (a int,b int);
20. insert into t1 values (1,1),(1,null);
21. mysql> select sleep(a) from t1;
22. +----------+
23. | sleep(a) |
24. +----------+
25. |        0 |
26. |        0 |
27. +----------+
28. 2 rows in set (2.01 sec)