# 比较日期

__*DATEDIFF 函数*__

+ `DATEDIFF(expr1, expr2)`: 返回两个 DATETIME 值之间的天数
  + 例如:
    + `select DATEDIFF(now(),'2022-02-22'), DATEDIFF('2022-02-22',NOW());` 
```
tidb> SELECT DATEDIFF(now(),'2022-02-22'), DATEDIFF('2022-02-22',NOW());
+------------------------------+------------------------------+
| DATEDIFF(now(),'2022-02-22') | DATEDIFF('2022-02-22',NOW()) |
+------------------------------+------------------------------+
|                          -44 |                           44 |
+------------------------------+------------------------------+
1 row in set (0.00 sec)
```
----------------------------------------------------------------------------
- DATEDIFF()	返回两个日期间隔的天数