TSQL - 小于或大于日期
我想生成一个查询，显示如果 startdate 小于 4 个月，则给出 5%，如果它大于 4 个月给出 10%.
I would like to produce a query that shows if startdate is less than 4 months old give 5% if its older than 4 months give 10%.
我正在使用 SQLFiddle，但没有得到正确的输出.目前它在所有列上给我 5% 或者如果我替换
I am using SQLFiddle and I not getting the right output. At the moment it’s giving me 5% on all the columns or if I replace
SET Discount = ''
到
SET Discount = '5%'
查询成功但不显示数据.
It will query successfully but does not show data.
这是我做的代码...
Declare
startdate date,
finishdate date,
Discount varchar(4)
UPDATE Persons
SET [Discount] = ' '
SELECT *, DATEADD(MM,-4,startdate) AS TADate
FROM Persons
WHERE Discount = '5%' AND startdate < dateadd(month,-4,getdate()) OR
Discount = '10%' AND startdate < dateadd(month,4,getdate())
如果有人可以帮助我，请提前致谢.
Thanks in advance if anyone can help me.
推荐答案
在update中使用case语句根据date分配折扣
Use case statement in update to allocate discount based on date
像这样尝试update
UPDATE Persons SET [Discount] = case
when startdate > dateadd(month,-4,getdate()) and startdate <= getdate() then '5%'
when startdate < dateadd(month,-4,getdate()) Then '10%'
End
SELECT * FROM Persons
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