sql server中的动态分组依据

SELECT CASE 
         WHEN CustomerType = 'A' THEN 'Type A'
         WHEN CustomerType = 'B' THEN 'Type B'
         ELSE 'Other'
       END AS GroupBy,
       SUM(SalesAmount) AS TotalSales
FROM Sales
GROUP BY CASE 
           WHEN CustomerType = 'A' THEN 'Type A'
           WHEN CustomerType = 'B' THEN 'Type B'
           ELSE 'Other'
         END;

DECLARE @ColumnName NVARCHAR(50) = 'CustomerType'

DECLARE @SQL NVARCHAR(MAX) = 'SELECT ' + @ColumnName + ' AS GroupBy,
                                     SUM(SalesAmount) AS TotalSales
                              FROM Sales
                              GROUP BY ' + @ColumnName

EXEC sp_executesql @SQL;