不在结果

Question

我正在尝试优化此选择，因为在CASE中有相同的选择两次，查询需要两次这么长时间才能运行：

SELECT sc.ID, 
      (CASE WHEN (SELECT SUM(scu.OK) 
                    FROM `SCU` scu 
                    WHERE scu.ID = _ID
                        AND scu.CCC = sc.ID
                    GROUP BY scu.ISC)
       IS NULL THEN 0 ELSE 
                    (SELECT SUM(scu.OK) 
                    FROM `SCU` scu 
                        WHERE scu.ID = _ID
                            AND scu.CCC = sc.ID
                        GROUP BY scu.ISC)
      END )as 'STATUS'
FROM    ( SELECT `ID` 
            FROM `STORE`
            WHERE `STATE`=1
            ORDER BY `NUMBERIN` DESC) sc
GROUP BY sc.ID;

我试过这样的事情

SELECT sc.ID, 
       @STATUS:=(SELECT SUM(scu.OK) 
                    FROM `SCU` scu 
                    WHERE scu.ID = _ID
                        AND scu.CCC = sc.ID
                    GROUP BY scu.ISC),
      (CASE WHEN @STATUS
       IS NULL THEN 0 ELSE @STATUS
       END ) as 'STATUS'
FROM    ( SELECT `ID` 
            FROM `STORE`
            WHERE `STATE`=1
            ORDER BY `NUMBERIN` DESC) sc
GROUP BY sc.ID;

但它返回了另一个包含 @STATUS 变量的列，但它不应该。 结果应具有ID和STATUS列。好吗？

Answer 1

最简单的事情是COALESCE - 可以用来替换具有特定值的NULL。

SELECT sc.ID, 
      COALESCE((SELECT SUM(scu.OK) 
                    FROM `SCU` scu 
                    WHERE scu.ID = _ID
                        AND scu.CCC = sc.ID
                    GROUP BY scu.ISC),0) as 'STATUS'      
FROM    ( SELECT `ID` 
            FROM `STORE`
            WHERE `STATE`=1
            ORDER BY `NUMBERIN` DESC) sc
GROUP BY sc.ID;

Answer 2

我认为您可以使用IFNULL执行以下操作：

SELECT sc.ID, 
       IFNULL(@STATUS:=(SELECT SUM(scu.OK) 
                    FROM `SCU` scu 
                    WHERE scu.ID = _ID
                        AND scu.CCC = sc.ID
                    GROUP BY scu.ISC),0,@STATUS) AS `STATUS`
FROM    ( SELECT `ID` 
            FROM `STORE`
            WHERE `STATE`=1
            ORDER BY `NUMBERIN` DESC) sc
GROUP BY sc.ID;

Answer 3

这个怎么样？

Select 
id, 
      (CASE WHEN status
       IS NULL THEN 0 ELSE status
       END ) as 'STATUS'
from
(SELECT sc.ID, 
       (SELECT SUM(scu.OK) 
                    FROM `SCU` scu 
                    WHERE scu.ID = _ID
                        AND scu.CCC = sc.ID
                    GROUP BY scu.ISC) as status
FROM    ( SELECT `ID` 
            FROM `STORE`
            WHERE `STATE`=1
            ORDER BY `NUMBERIN` DESC) sc
GROUP BY sc.ID) temp

抱歉，我在智能手机中输入了它们。 希望它有所帮助