更新的问题:
ALTER PROC Proc_Test
(
    @GrpBy as varchar(20) 
)
AS
Declare @TableTax table(
Taxid int,
TaxRange nvarchar(20),
MinLimit int,
MaxLimit int
)
SELECT t1.*     
FROM 
(
    SELECT  
        GroupBy = CASE @GrpBy 
                    WHEN 'JobGrade' THEN Employee.Grade                 
                    WHEN 'Tax Slab' THEN tblTax.TaxRange
                  END, (20 more calculated columns)
    FROM @TableTax AS tblTax, Employee
        LEFT JOIN Grade on Grade.Grade = Employee.Grade     
    WHERE
    Employee.Salary between tblTax.MinLimit and tblTax.Maxlimit     
    GROUP BY    
        CASE @GrpBy
                    WHEN 'JobGrade' THEN Employee.Grade                 
                    WHEN 'Tax Slab' THEN tblTax.TaxRange
                  END   
) AS t1
ORDER BY GroupBy
我想按 TaxId 订购结果。此 order by 仅适用于在前端选择 Tax Slab 的情况。