如何計算MySQL中的內部連接和多個條件

我想要一個查詢，每次使用每種顏色時都會計數。如何計算MySQL中的內部連接和多個條件

tbl_places是保存來自幾個枚舉表的數據的主表。 tbl_places爲不同建築物中特定樓層的顏色保留相應的INT值。 `

tbl_paintcolor是一個包含2列的枚舉表：值和顏色。

我不知道如何將ON子句與我要在tbl_places中計數的特定列相關聯。

SELECT 
    `tbl_paintcolor`.`Color` AS Paint_Color, 
    count(`tbl_places`.`blg1floor1_color`) AS Blg1Floor1, 
    count(`tbl_places`.`blg1floor2_color`) AS Blg1Floor2, 
    count(`tbl_places`.`blg1floor3_color`) AS Blg1Floor3 
FROM `tbl_places` 
INNER JOIN `tbl_paintcolor` ON (`tbl_places`.`blg1floor1_color`=`tbl_paintcolor`.`Value` OR `tbl_places`.`blg1floor2_color`=`tbl_paintcolor`.`Value`) 
GROUP BY `tbl_paintcolor`.`Color`

該查詢結束了或多或少地計算同一列。

如何將ON子句中的條件表達式與我想在SELECT子句中計算的列相關聯？

我想查詢爲每個特定樓層輸出一列，每行記錄顏色被找到的時間。此查詢的輸出將被結構化：

╔════════╦════════════╦════════════╦════════════╗ 
║ Color ║ Blg1Floor1 ║ Blg1Floor2 ║ Blg1Floor3 ║ etc... 
╠════════╬════════════╬════════════╬════════════╣ 
║ red ║  23  ║  23  ║  23  ║ 
║ orange ║  23  ║  23  ║  23  ║ 
║ yellow ║  23  ║  23  ║  23  ║ 
╚════════╩════════════╩════════════╩════════════╝

等

感謝您的時間，並道歉，如果這還不清楚，我是很新的SQL。

來源

2015-11-03 Bret Shandro

您的查詢不罷工我是錯的。你目前的產出是多少？ –

它爲每列輸出相同的計數。我認爲我的問題在OR語句中。我正在尋找一種更好的方法來將ON子句鏈接到我的SELECT子句 –

如果您向我們展示數據和查詢輸出的可重複示例，可能會有所幫助。 –

SUM()與CASE WHEN將做的伎倆。

SELECT 
     `tbl_paintcolor`.`Color` AS Paint_Color, 
     SUM(CASE WHEN `tbl_places`.`blg1floor1_color` IS NOT NULL THEN 1 ELSE 0 END) AS Blg1Floor1, 
     SUM(CASE WHEN `tbl_places`.`blg1floor2_color` IS NOT NULL THEN 1 ELSE 0 END) AS Blg1Floor2, 
     SUM(CASE WHEN `tbl_places`.`blg1floor2_color` IS NOT NULL THEN 1 ELSE 0 END) AS Blg1Floor3 
    FROM `tbl_places` 
    LEFT JOIN `tbl_paintcolor` 
    ON (`tbl_places`.`blg1floor1_color`=`tbl_paintcolor`.`Value` 
           OR `tbl_places`.`blg1floor2_color`=`tbl_paintcolor`.`Value`) 
    GROUP BY `tbl_paintcolor`.`Color`

希望這有助於

來源

2015-11-03 04:07:45

謝謝@Subin！這對我有用。 –

我想你應該嘗試用SUM更換COUNT

SELECT 
    `tbl_paintcolor`.`Color` AS Paint_Color, 
    SUM(IF(`tbl_places`.`blg1floor1_color`=`tbl_paintcolor`.`Value`, 1, 0)) AS Blg1Floor1, 
    SUM(IF(`tbl_places`.`blg1floor2_color`=`tbl_paintcolor`.`Value`, 1, 0)) AS Blg1Floor2, 
    SUM(IF(`tbl_places`.`blg1floor3_color`=`tbl_paintcolor`.`Value`, 1, 0)) AS Blg1Floor3, 
FROM `tbl_places` 
INNER JOIN `tbl_paintcolor` ON (
     `tbl_places`.`blg1floor1_color`=`tbl_paintcolor`.`Value` 
     OR `tbl_places`.`blg1floor2_color`=`tbl_paintcolor`.`Value` 
     OR `tbl_places`.`blg1floor3_color`=`tbl_paintcolor`.`Value` 
) 
GROUP BY `tbl_paintcolor`.`Color`

或另一種方式，你可以嘗試是

SELECT `tbl_paintcolor`.`Color` AS Paint_Color, 
    (SELECT COUNT(1) AS qty FROM `tbl_places` p1 WHERE p1.`blg1floor1_color`=`tbl_paintcolor`.`Value`) AS Blg1Floor1, 
    (SELECT COUNT(1) AS qty FROM `tbl_places` p2 WHERE p2.`blg1floor2_color`=`tbl_paintcolor`.`Value`) AS Blg1Floor2, 
    (SELECT COUNT(1) AS qty FROM `tbl_places` p3 WHERE p3.`blg1floor3_color`=`tbl_paintcolor`.`Value`) AS Blg1Floor3 
FROM `tbl_paintcolor`

來源

2015-11-03 04:19:34 David

感謝@David，您的第一個腳本對我更好，因爲我有日期列，並且我可以使用where子句來聚焦查詢 –

如何計算MySQL中的內部連接和多個條件

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