ORDER BY子句的CASE WHEN语句

Question

我正在使用SQL Server 2008 R2。

我想要对表中的记录进行基于优先级的排序。

这样我在ORDER BY子句中使用CASE WHEN语句。 ORDER BY子句如下：

ORDER BY 
CASE WHEN TblList.PinRequestCount <> 0 THEN TblList.PinRequestCount desc, TblList.LastName ASC, TblList.FirstName ASC, TblList.MiddleName ASC END, 
CASE WHEN TblList.HighCallAlertCount <> 0 THEN TblList.HighCallAlertCount desc, TblList.LastName ASC, TblList.FirstName ASC, TblList.MiddleName ASC END,
Case WHEN TblList.HighAlertCount <> 0 THEN TblList.HighAlertCount DESC, TblList.LastName ASC, TblList.FirstName ASC, TblList.MiddleName ASC END,
CASE WHEN TblList.MediumCallAlertCount <> 0 THEN TblList.MediumCallAlertCount DESC, TblList.LastName ASC, TblList.FirstName ASC, TblList.MiddleName ASC END,
Case WHEN TblList.MediumAlertCount <> 0 THEN TblList.MediumAlertCount DESC, TblList.LastName ASC, TblList.FirstName ASC, Patlist.MiddleName ASC END

但是它Incorrect syntax near the keyword 'desc'给出了Incorrect syntax near the keyword 'desc'

有什么办法吗？

我也可以有：

TblList.PinRequestCount <> 0 and TblList.HighCallAlertCount <> 0 and
TblList.HighAlertCount <> 0` and TblList.MediumCallAlertCount <> 0 and  
TblList.MediumAlertCount <> 0 

与此同时。

Answer 1

CASE是一个表达式 -它返回单个标量值（每行）。 它无法返回其他语法分析树的复杂部分，例如SELECT语句的ORDER BY子句。

看来您只需要：

ORDER BY 
CASE WHEN TblList.PinRequestCount <> 0 THEN TblList.PinRequestCount END desc,
CASE WHEN TblList.HighCallAlertCount <> 0 THEN TblList.HighCallAlertCount END desc, 
Case WHEN TblList.HighAlertCount <> 0 THEN TblList.HighAlertCount END DESC,
CASE WHEN TblList.MediumCallAlertCount <> 0 THEN TblList.MediumCallAlertCount END DESC,
Case WHEN TblList.MediumAlertCount <> 0 THEN TblList.MediumAlertCount END DESC,
TblList.LastName ASC, TblList.FirstName ASC, TblList.MiddleName ASC

或可能：

ORDER BY 
CASE
   WHEN TblList.PinRequestCount <> 0 THEN TblList.PinRequestCount
   WHEN TblList.HighCallAlertCount <> 0 THEN TblList.HighCallAlertCount
   WHEN TblList.HighAlertCount <> 0 THEN TblList.HighAlertCount
   WHEN TblList.MediumCallAlertCount <> 0 THEN TblList.MediumCallAlertCount
   WHEN TblList.MediumAlertCount <> 0 THEN TblList.MediumAlertCount
END desc,
TblList.LastName ASC, TblList.FirstName ASC, TblList.MiddleName ASC

分辨上面的（或其他）内容是您要寻找的，这有点棘手，因为您已经a）没有说明您要达到的实际排序顺序，并且b）没有提供任何示例数据，并且预期的结果，从中我们可以尝试推断你想达到的实际排序顺序。

---

这可能是我们正在寻找的答案：

ORDER BY 
CASE
   WHEN TblList.PinRequestCount <> 0 THEN 5
   WHEN TblList.HighCallAlertCount <> 0 THEN 4
   WHEN TblList.HighAlertCount <> 0 THEN 3
   WHEN TblList.MediumCallAlertCount <> 0 THEN 2
   WHEN TblList.MediumAlertCount <> 0 THEN 1
END desc,
CASE
   WHEN TblList.PinRequestCount <> 0 THEN TblList.PinRequestCount
   WHEN TblList.HighCallAlertCount <> 0 THEN TblList.HighCallAlertCount
   WHEN TblList.HighAlertCount <> 0 THEN TblList.HighAlertCount
   WHEN TblList.MediumCallAlertCount <> 0 THEN TblList.MediumCallAlertCount
   WHEN TblList.MediumAlertCount <> 0 THEN TblList.MediumAlertCount
END desc,
TblList.LastName ASC, TblList.FirstName ASC, TblList.MiddleName ASC

Answer 2

来自这里的另一个简单示例。

SELECT * FROM dbo.Employee
ORDER BY 
 CASE WHEN Gender='Male' THEN EmployeeName END Desc,
 CASE WHEN Gender='Female' THEN Country END ASC

Answer 3

您需要使用END结束每个案例（在desc之前）

Answer 4

declare @OrderByCmd  nvarchar(2000)
declare @OrderByName nvarchar(100)
declare @OrderByCity nvarchar(100)
set @OrderByName='Name'    
set @OrderByCity='city'
set @OrderByCmd= 'select * from customer Order By '+@OrderByName+','+@OrderByCity+''
EXECUTE sp_executesql @OrderByCmd