加法、减法、乘法和除法运算符如何处理 MySQL 表中存储的日期值？

当我们尝试对表中存储的日期值进行此类操作时，MySQL 会将日期值假设为数字并执行算术运算。

假设我们有一个名为“example”的表在“orderdate”列中有一个日期值，然后进行算术运算将澄清上述内容 -

mysql> select * from example;
+------------+
| orderdate  |
+------------+
| 2017-05-25 |
+------------+
1 row in set (0.00 sec)

mysql> select orderdate+10 from example;
+--------------+
| orderdate+10 |
+--------------+
|     20170535 |
+--------------+
1 row in set (0.00 sec)

mysql> select orderdate*10 from example;
+--------------+
| orderdate*10 |
+--------------+
|    201705250 |
+--------------+
1 row in set (0.00 sec)

mysql> select orderdate-10 from example;
+--------------+
| orderdate-10 |
+--------------+
|     20170515 |
+--------------+
1 row in set (0.00 sec)

mysql> select orderdate/10 from example;
+--------------+
| orderdate/10 |
+--------------+
|    2017052.5 |
+--------------+
1 row in set (0.00 sec)