MySql：如何將行號與聯接查詢語句一起使用？

Question

我有一個MySQL語句，該語句連接了2個表，並以“觸摸”字段的Desc順序顯示結果。 這是我的SQL語句

SELECT @rownum := @rownum +1 rownum, 
(IF( dm.Brand_FULL = '1', dd.Device_Brand, dm.Brand_Full )) AS Brand,
dd.Device_Model AS Model, 
CONCAT( dm.Service_provider, ' ', dm.Model_Full ) AS 'Marketing Name', 
max( Touch_Count ) AS Touch FROM Device_Details dd 
JOIN Device_Models dm ON dd.Device_Model = dm.Model_Short, 
(SELECT @rownum :=0 )r GROUP BY dd.Device_Model ORDER BY Touch_Count DESC

這給我這樣的結果

結果是perferct，其結果基於Touch字段的降序。現在的問題是rownum的順序不正確。 那么如何修改mySQL語句，以便我可以按順序獲取rownum而不更改Touch字段的DESC順序。

Answer 1

使用子查詢：

SELECT
    @rownum := @rownum + 1 AS rownum,
    T1.*
FROM
(
    SELECT
        IF(dm.Brand_Full = '1', dd.Device_Brand, dm.Brand_Full) AS Brand,
        dd.Device_Model AS Model, 
        CONCAT(dm.Service_provider, ' ', dm.Model_Full) AS 'Marketing Name', 
        MAX(Touch_Count) AS Touch
    FROM Device_Details dd 
    JOIN Device_Models dm
    ON dd.Device_Model = dm.Model_Short
    GROUP BY dd.Device_Model
) AS T1, (SELECT @rownum := 0) AS r
ORDER BY Touch DESC