从 MS-SQL Server 查询转换为 MySQL 和 DATEDIFF()

Question

我一直在将以下 MS-SQL Server 的查询转换为 MySQL，我被困在这个日期部分。谁能告诉我我在这里做错了什么？

原始 MS-SQL 查询（工作）

select  top 4
    [Mon]=sum(case when datename(weekday, vrdate) = 'Monday' then namount else 0 end),
    [Tue]=sum(case when datename(weekday, vrdate) = 'Tuesday' then namount else 0 end),
    [Wed]=sum(case when datename(weekday, vrdate) = 'Wednesday' then namount else 0 end),
    [Thu]=sum(case when datename(weekday, vrdate) = 'Thursday' then namount else 0 end),
    [Fri]=sum(case when datename(weekday, vrdate) = 'Friday' then namount else 0 end),
    [Sat]=sum(case when datename(weekday, vrdate) = 'Saturday' then namount else 0 end),
    [Sun]=sum(case when datename(weekday, vrdate) = 'Sunday' then namount else 0 end)
from    stockmain
where    etype = 'sale' and  DATEDIFF(MONTH, vrdate, getDate()) = 0
group by datepart(week, vrdate)
order by datepart(week, vrdate) ;

各个 MySQL 查询（不工作）

下面是相应的 MySQL 查询，我被困在 DATEDIFF 中的 WHERE 子句中。

select 
        sum(case when date_format(vrdate, '%W') = 'Monday' then namount else 0 end) as 'Mon',
        sum(case when date_format(vrdate, '%W') = 'Tuesday' then namount else 0 end) as 'Tue',
        sum(case when date_format(vrdate, '%W') = 'Wednesday' then namount else 0 end) as 'Wed',
        sum(case when date_format(vrdate, '%W') = 'Thursday' then namount else 0 end) as 'Thu',
        sum(case when date_format(vrdate, '%W') = 'Friday' then namount else 0 end) as 'Fri',
        sum(case when date_format(vrdate, '%W') = 'Saturday' then namount else 0 end) as 'Sat',
        sum(case when date_format(vrdate, '%W') = 'Sunday' then namount else 0 end) as 'Sun'
from    stockmain
where    etype = 'sale' and DATEDIFF(MONTH, vrdate, CURDATE()) = 0
group by WEEK(VRDATE)
order by WEEK(VRDATE) desc
LIMIT 4

Answer 1

datediff 在 SQL Server 上的工作方式与 MySQL 等效的是 timestampdiff。

WHERE TIMESTAMPDIFF(month, vrdate, curdate()) = 0

以下可能是等价的，具体取决于datediff 在计算前一个月如何舍入：

WHERE MONTH(vrdate) = MONTH(CURDATE())