mysql - 从当前月份开始计算年龄

Question

我有以下代码可以从今天的日期计算一个人的出生日期，效果很好

    SELECT application.applicationLastName, application.applicationFirstName, application.applicationDoB, 
ROUND(DATEDIFF(NOW(), applicationDoB) / 365.2425,1) AS age, application.applicationID, application.applicationAcknowledged, application.applicationContacted, application.applicationDate
FROM application
ORDER BY application.applicationDate ASC 

但是，我被要求从本月 1 日开始计算他们的年龄并尝试过

SELECT application.applicationLastName, application.applicationFirstName, application.applicationDoB, DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0) AS CURMONTH, 
ROUND(DATEDIFF(CURMONTH(), applicationDoB) / 365.2425,1) AS age, application.applicationID, application.applicationAcknowledged, application.applicationContacted, application.applicationDate
FROM application
ORDER BY application.applicationDate ASC

但是我收到以下错误：调用本机函数'DATEDIFF'中的参数计数不正确

Answer 1

你不应该使用CURMONTH(). 而是将今天的日期格式化为本月 1 日。

使用以下查询：

SELECT application.applicationLastName, application.applicationFirstName, application.applicationDoB, DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0) AS CURMONTH, 
ROUND(DATEDIFF(DATE_FORMAT(NOW() ,'%Y-%m-01'), applicationDoB) / 365.2425,1) AS age, application.applicationID, application.applicationAcknowledged, application.applicationContacted, application.applicationDate
FROM application
ORDER BY application.applicationDate ASC

Answer 2

您正在使用： DATEDIFF(CURMONTH(), applicationDoB)

在你的代码中。但是 CURMONTH() 只给你当前日期的月份，而 applicationDoB 给你一个完整的日期。您还需要将 CURMONTH() 替换为对应于完整日期的表达式（当月的第一天）。