mysql数据库求字段的最大值和最小值

概述

MySQL的GREATEST函数求最大值。
MySQL的LEAST函数求最小值。

示例:

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mysql> SELECT GREATEST(DATE('2016-05-02'), DATE('2015-05-02'), DATE('2017-05-02'));  
+----------------------------------------------------------------------+
| GREATEST(DATE('2016-05-02'), DATE('2015-05-02'), DATE('2017-05-02')) |
+----------------------------------------------------------------------+
| 2017-05-02                                                           |
+----------------------------------------------------------------------+
1 row in set (0.03 sec)

mysql> SELECT LEAST(DATE('2016-05-02'), DATE('2015-05-02'), DATE('2017-05-02'));   
+-------------------------------------------------------------------+
| LEAST(DATE('2016-05-02'), DATE('2015-05-02'), DATE('2017-05-02')) |
+-------------------------------------------------------------------+
| 2015-05-02                                                        |
+-------------------------------------------------------------------+
1 row in set (0.00 sec)