需要查找存儲在多個列中的值的計數

Question

我希望能夠根據表中的另一列計算特定值在列中出現的次數。下面是示例表：

Color Shape  Col1 Col2 Col3 Col4 Col5 
-------------------------------------------------------- 
Blue Circle  Blue Null Yellow Null Null 
Blue Circle  Blue Null Null Null Black 
Blue Circle  Null Null Null Null Null 
Yellow Square  Null Null Null Null Null 
Yellow Square  Null Yellow Null Null Null 
Yellow Square  Null Null Null Null Null 
Yellow Square  Green Null Null Yellow Null 
Yellow Square  Null Null Null Null Null 
Green Rectangle Null Null Null Null Green 
Orange Triangle Gray White Null Null Orange 
Orange Triangle Null Orange Null Null Null 

我需要的結果是見下表：

Color Shape  Col1 Col2 Col3 Col4 Col5 
---------------------------------------------------- 
Blue Circle  2 0  0  0  0 
Yellow Square  0 1  0  1  0 
Green Rectangle 0 0  0  0  1 
Orange Triangle 0 1  0  0  1 

這個查詢是不是給我的願望了：

select 
    Color, Shape, 
    count(Col1) as Col1, count(Col2) as Col2, 
    count(Col3) as Col3, count(Col4) as Col4, count(Col5) as Col5 
from 
    Sample_Table 
group by 
    Color, Shape 

有誰知道如何獲得慾望輸出？

Answer 1

使用CASE表達式進行條件計數：

select 
    Color, Shape, 
    count(case when Color = Col1 then 1 end) as Col1, 
    count(case when Color = Col2 then 1 end) as Col2, 
    count(case when Color = Col3 then 1 end) as Col3, 
    count(case when Color = Col4 then 1 end) as Col4, 
    count(case when Color = Col5 then 1 end) as Col5 
from 
    Sample_Table 
group by 
    Color, Shape