# timediff
## description
### Syntax

`TIME TIMEDIFF(DATETIME expr1, DATETIME expr2)`


TIMEDIFF返回两个DATETIME之间的差值

TIMEDIFF函数返回表示为时间值的expr1 - expr2的结果，返回值为TIME类型

## example

```
mysql> SELECT TIMEDIFF(now(),utc_timestamp());
+----------------------------------+
| timediff(now(), utc_timestamp()) |
+----------------------------------+
| 08:00:00                         |
+----------------------------------+

mysql> SELECT TIMEDIFF('2019-07-11 16:59:30','2019-07-11 16:59:21');
+--------------------------------------------------------+
| timediff('2019-07-11 16:59:30', '2019-07-11 16:59:21') |
+--------------------------------------------------------+
| 00:00:09                                               |
+--------------------------------------------------------+

mysql> SELECT TIMEDIFF('2019-01-01 00:00:00', NULL);
+---------------------------------------+
| timediff('2019-01-01 00:00:00', NULL) |
+---------------------------------------+
| NULL                                  |
+---------------------------------------+
```

##keyword

    TIMEDIFF