複雜的查詢 - 用分組的列

Question

幾張桌子，我有表：

Worker (ID, Name) 

Box (ID, Name, ID_Worker) 

BoxColor (ID, Name) 
BoxSize (ID, Name) 

Item(ID, ID_box, ID_BoxColor, ID_BoxSize) 

所以我們誰創建項目，並把它們自己的箱子裏面的工人。 對於我的祕密工作的緣故，我改變了話題，從我的祕密之一EHM箱;）

我想創建raport有列：

Worker.Name | BoxSize.Name | BoxColor(id=0) | BoxColor(id=1) | BoxColor(id=2) 

表盒中其它raports使用，因此這桌子的結構可以改變。

我例如想要得到的是：

分組名工人和每個BoxSize，有在列每種顏色計數。 例如：

John | X | 2 | 4 | 0 | 
John | XL | 5 | 1 | 0 | 
John | XXL | 2 | 0 | 0 | 
John | S | 3 | 1 | 0 | 
Adam | X | 5 | 4 | 0 | 
Adam | XL | 1 | 3 | 0 | 
Adam | S | 0 | 1 | 0 | 
.... 

BoxColor是沒有那麼多顏色的表，以便與不同的子可以硬編碼選擇像

(select count(*) from BoxColor where ID = 0) 
(select count(*) from BoxColor where ID = 1) 
(select count(*) from BoxColor where ID = 2) 

我試圖做這樣的事情，但查詢答循環它永遠不會停止 「思考」

select Worker.Name, BoxSize.Name, 
(select count(*) from BoxColor as BoxColor2, Box as Box2, Item as Item2 
    where Box2.ID_Worker = Worker.ID and 
     Item2.ID_Box = Box2.ID and 
     Item2.ID_BoxColor = BoxColor2.ID) and 
     BoxColor.ID = 0) as Red, 
(select count(*) from BoxColor as BoxColor2, Box as Box2, Item as Item2 
    where Box2.ID_Worker = Worker.ID and 
     Item2.ID_Box = Box2.ID and 
     Item2.ID_BoxColor = BoxColor2.ID) and 
     BoxColor.ID = 1) as Green, 
(select count(*) from BoxColor as BoxColor2, Box as Box2, Item as Item2 
    where Box2.ID_Worker = Worker.ID and 
     Item2.ID_Box = Box2.ID and 
     Item2.ID_BoxColor = BoxColor2.ID) and 
     BoxColor.ID = 2) as Blue, 
from Worker, BoxSize, Box, Item 
where 
    Item.ID_Worker = Worker.ID and 
    Item.ID_Box = Box.ID 
    Item.ID_BoxSize = BoxSize.ID 
group by Worker.Name, BoxSize.Name 
having Red > 0, Blue > 0, Green > 0 
order by 1, 2 

Answer 1

也許是這樣的：

SELECT 
    Worker.Name, 
    BoxSize.Name, 
    SUM(CASE WHEN BoxColor.id=0 THEN 1 ELSE 0 END) AS BoxColor_0, 
    SUM(CASE WHEN BoxColor.id=1 THEN 1 ELSE 0 END) AS BoxColor_1, 
    SUM(CASE WHEN BoxColor.id=2 THEN 1 ELSE 0 END) AS BoxColor_2  
FROM 
    Worker 
    JOIN Box 
     ON Worker.ID=Box.ID_Worker 
    JOIN Item 
     ON Item.ID_box=Box.ID 
    JOIN BoxColor 
     ON BoxColor.ID=Item.ID_BoxColor 
    JOIN BoxSize 
     ON BoxSize.ID=Item.ID_BoxSize 
GROUP BY 
    Worker.Name, 
    BoxSize.Name