# **SLEEP()**

## **Function Description**

The `SLEEP()` function pauses (sleep) the specified number of seconds for the current query. The result will return 0.

## **Function Syntax**

```text
>
SLEEP(duration)
```

## **Parameter definition**

| Parameters | Description |
| ---- | ---- |
| duration | Required. The length of sleep in seconds. It should be greater than or equal to 0 and can take a fractional part. |

## **Return value**

- When `SLEEP()` returns normally (without interruption), it returns 0.

- When the interrupted query calls unique results, it returns 1 and the query itself does not return an error.

   Examples are as follows:

   1. Execute the following command in session 1, query the current connection_id, and execute the `SLEEP()` function:

       ```text
       mysql> select connection_id();
       +-----------------------+
       | connection_id() |
       +-----------------------+
       | 1476 |
       +-----------------------+
       1 row in set (0.03 sec)
       mysql> select sleep(200);
       ```

   2. At this time, open a new session, interrupt session 1, and execute the following command:

       ```text
       mysql> kill 1476;
       Query OK, 0 rows affected (0.00 sec)
       ```

    3. View the results of session 1:

        ```
        mysql> select sleep(200);
        +----------------+
        | sleep(200) |
        +----------------+
        | 1 |
        +----------------+
        1 row in set (26.50 sec)
        ```

- SLEEP() returns an error when some query is interrupted, for example:

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

## **Example**

```text
-- without interruption
mysql> SELECT SLEEP(1);
+-------------+
| sleep(1) |
+-------------+
| 0 |
+-------------+
1 row in set (1.01 sec)

-- without interruption
mysql> SELECT SLEEP(1000);
+-----------------+
| sleep(1000) |
+-----------------+
| 0 |
+-----------------+
1 row in set (18 min 20.87 sec)

create table t1 (a int,b int);
insert into t1 values (1,1),(1,null);
mysql> select sleep(a) from t1;
+-------------+
| sleep(a) |
+-------------+
| 0 |
| 0 |
+-------------+
2 rows in set (2.01 sec)
```