mysql - SQL 2012 我的选择中的 MAX 未显示最大值

Question

抱歉，格式问题!我不知道它在这个网站上是否有效:(

我试图只返回 1 月份销售表中最高的总计，但它返回该月的所有销售，而不仅仅是最高的销售。

select
  EMP.FirstName,
  EMP.LastName,
  EMP.Email,
  SAL.SaleNumber,
  SAL.SaleDate,
  max(SAL.Total) Total
from 
  Employee EMP
  INNER JOIN Sale SAL
    ON EMP.EmployeeNumber = SAL.EmployeeNumber

--Assuming the month is January of 2015, because there were no sales for this month (March).
where
  SAL.SaleDate between '20150101 00:00:00.000' and '20150131 23:59:59.997'

group by
  EMP.FirstName,
  EMP.LastName,
  EMP.Email,
  SAL.SaleNumber,
  SAL.SaleDate,
  SAL.Total

Answer 1

我假设您想获得每个员工在给定时间范围内的最大销售额？如果是这样，一种选择是使用排名函数，例如 row_number :

with cte as (
select
  EMP.FirstName,
  EMP.LastName,
  EMP.Email,
  SAL.SaleNumber,
  SAL.SaleDate,
  SAL.Total,
  row_number() over (partition by EMP.EmployeeNumber 
                     order by SAL.Total DESC) rn
from 
  Employee EMP
  INNER JOIN Sale SAL
    ON EMP.EmployeeNumber = SAL.EmployeeNumber
where
  SAL.SaleDate >= '20150101 00:00:00.000' and 
  SAL.SaleDate < '20150201 00:00:00.000'
)
select *
from cte
where rn = 1

另请注意，我建议使用 >=和<对于这种类型的日期过滤。