如何检查日期是否在MySQL的范围内？

Question

为什么我会为这个类似的查询得到不同的结果？

SELECT CASE WHEN CONCAT(2011, '-1-1') BETWEEN '2011-01-01' AND '2011-03-31' THEN 1 ELSE 0 END AS status; 
+--------+ 
| status | 
+--------+ 
|  0 | 
+--------+ 

SELECT CASE WHEN CONCAT(2011, '-1-1') BETWEEN '2011-1-1' AND '2011-3-31' THEN 1 ELSE 0 END AS status; 
+--------+ 
| status | 
+--------+ 
|  1 | 
+--------+ 

Answer 1

因为您正在比较字符串，而不是日期。

将字符串转换为日期的最简单方法是在DATE（）中换行。

SELECT CASE WHEN DATE(CONCAT(2011, '-1-1')) 
      BETWEEN DATE('2011-1-1') AND DATE('2011-3-31') 
      THEN 1 ELSE 0 END AS status; 

http://dev.mysql.com/doc/refman/5.0/en/datetime.html

您也可以让你的查询更短，因为MySQL的返回布尔为1/0本身。

SELECT DATE(CONCAT(2011, '-1-1')) 
      BETWEEN DATE('2011-1-1') AND DATE('2011-3-31') as status; 

Answer 2

您正在比较字符串，而不是日期。尝试明确地转换为所需的数据类型：

SELECT CASE WHEN CAST(CONCAT(2011, '-1-1') AS DATETIME) BETWEEN CAST('2011-01-01' AS DATETIME) AND CAST('2011-03-31' AS DATETIME) THEN 1 ELSE 0 END AS status; 

Answer 3

因为它正在做字符串比较。你应该使用mysl date函数。

SELECT CASE WHEN date(CONCAT(2011, '-1-1')) BETWEEN date('2011-1-1') AND date('2011-3-31') THEN 1 ELSE 0 END AS status;