設置CASE語句，以便所有的結果類型爲VARCHAR

Question

我使用下面的查詢，但得到的錯誤

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

我相信它，因爲第二行是返回一個整數，其餘的不是，是正確的？

我不打算計算這個字段，所以如果他們都需要是相同類型的值，讓第二行返回爲varchar會很好。我嘗試過使用'convert'，但是我不想我認爲我的語法沒錯。

,(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

嘗試以下：

,(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

與 '野點' 定義的情況下爲varchar的結果。第二行產生int - 所以存在類型衝突。