使用sql查询计算上个月的月数

Question

我想计算直到上个月注册完成的月数。我将查询写成

SELECT count(MONTH(`regdate`) < MONTH(CURDATE()) AND YEAR(`regdate`) <= YEAR(CURDATE())) FROM `client_details` WHERE hospitalid='apollo123'

Answer 1

也许你想要这个：

select month(regdate), count(*)
  from client_details
  where regdate < curdate()
    and hospitalid = 'apollo123'
  group by month(regdate);

这将在curdate()之前的每个月为您提供当月发生的注册计数。

Answer 2

SELECT count (*)from (
select month(regdate)
from client_details
where regdate < curdate()
and hospitalid = 'apollo123'
group by month(regdate));

这将为您提供截至上个月注册时的月数。

Answer 3

一个解决方案是

select count(distinct(cast(MONTH(regdate) as nvarchar(10)) + cast(year(regdate) as nvarchar(10)))) from client_details where hospitalid = 'apollp123' and regdate < DATEADD(month, DATEDIFF(month, 0, GETDATE())-1, 0)

我在Sql Server上测试过这个，你应该调整mySql的代码。