資料庫查詢結果動態排序（三）：欄位編號參數化、CASE 巢狀運算式與數值排序字串化技巧

ALTER PROC GetSortedShippers
    @ColNumber AS INT
AS
SELECT *
FROM Shippers
ORDER BY
    CASE @ColNumber
        WHEN 1 THEN 
            CASE SIGN(ShipperID)
                WHEN -1 THEN '-'
                WHEN 0 THEN '+'
                WHEN 1 THEN '+'
                ELSE NULL
            END +
            RIGHT(REPLICATE('0', 10) + CAST(ABS(ShipperID) AS VARCHAR(10)), 10)
        WHEN 2 THEN CompanyName
        WHEN 3 THEN Phone
        ELSE NULL
    END