How to map stored procedures having dynamically pivoted fields

I have a stored procedure which gets pivot fields as a parameter (say @P) which splits by , and am pivoting for a table based on fields which the the @P includes them , i wanna map the stored procedure in EF . But don't know how to create a complex type with dynamic number of fields based on result of stored procedure. I have something like the fallowing:

CREATE PROC pr 
@p AS NVARCHAR(500)='[250], [251], [256], [257], [260]'
AS 
DECLARE @qy NVARCHAR(500)


SET @qy='SELECT VendorID, '+dbo.SetAliasForPivotingCols(@p)+'
        FROM 
        (SELECT PurchaseOrderID, EmployeeID, VendorID
        FROM Purchasing.PurchaseOrderHeader) p
        PIVOT
        (
        COUNT (PurchaseOrderID)
        FOR EmployeeID IN
        ( '+@p+' )
        ) AS pvt
        ORDER BY pvt.VendorID;
EXEC sp_executesql @qy

To attach alias after pivoted fields (imagine im not doing this if its complex) :

CREATE FUNCTION [dbo].[SetAliasForPivotingCols](@RequestedRscsId NVARCHAR(500))RETURNS `NVARCHAR(2000)`
BEGIN
SET @RequestedRscsId=','+@RequestedRscsId
DECLARE @ReturnValue NVARCHAR(2000)=''
DECLARE @CloseBraceIndex INT
DECLARE @Alias NVARCHAR(10)
WHILE LEN(@RequestedRscsId)>1
BEGIN
    SET @CloseBraceIndex=PATINDEX('%]%',@RequestedRscsId)
    SET @Alias=SUBSTRING(@RequestedRscsId,2,@CloseBraceIndex-1)
    SET @RequestedRscsId   =SUBST开发者_如何学运维RING(@RequestedRscsId,@CloseBraceIndex+1,LEN(@RequestedRscsId)-@CloseBraceIndex+1)
    SET @ReturnValue+=',SUM('+@Alias+')'+' AS '+SUBSTRING(@Alias,1,LEN(@Alias))
END
RETURN SUBSTRING(@ReturnValue,2,LEN(@ReturnValue))
END

any suggestion?

thank you.

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It is not possible. You must consume such stored procedure with classic ADO.NET.