设置CASE语句，以便所有的结果类型为VARCHAR

Question

我使用下面的查询，但得到的错误

'Conversion failed when converting the varchar value '8-14' to data type int.' 

我相信它，因为第二行是返回一个整数，其余的不是，是正确的？

我不打算计算这个字段，所以如果他们都需要是相同类型的值，让第二行返回为varchar会很好。我尝试过使用'convert'，但是我不想我认为我的语法没错。

,(case when AppointmentCancellationDate = null Then 'NoDate' 
when (datediff(day,BasicStartDate,AppointmentCancellationDate)) < '8' then (datediff(day,BasicStartDate,AppointmentCancellationDate)) 
when (datediff(day,BasicStartDate,AppointmentCancellationDate)) <15 then '8-14' 
when (datediff(day,BasicStartDate,AppointmentCancellationDate)) <22 then '15-21' 
Else '+22' end) as CancWindowGroup 

Answer 1

尝试以下：

,(case when AppointmentCancellationDate is null Then 'NoDate' 
when (datediff(day,BasicStartDate,AppointmentCancellationDate)) <8 then cast(datediff(day,BasicStartDate,AppointmentCancellationDate) as nvarchar(10)) 
when (datediff(day,BasicStartDate,AppointmentCancellationDate)) <15 then '8-14' 
when (datediff(day,BasicStartDate,AppointmentCancellationDate)) <22 then '15-21' 
Else '+22' end) as CancWindowGroup 

Answer 2

与 '野点' 定义的情况下为varchar的结果。第二行产生int - 所以存在类型冲突。