聚合，計數，案例和條款

Question

我是新來的，所以請耐心等待。

我正在寫一個查詢，我需要用兩個特定的值來計算的行數，

我已經使用下列以獲得在一個領域的不同值的結果，但我需要知道僅當另一個字段設置爲特定值時纔會生成結果。我把從以前的問題，關於這個站點如下：

COALESCE(count(case when CW.MAINJOBROLE = 2 THEN 1 end),0) as ALLJOBROLES_2, 
coalesce(count(case when CW.MAINJOBROLE = 3 then 1 end), 0) as ALLJOBROLES_3, 
coalesce(count(case when CW.MAINJOBROLE = 4 then 1 end), 0) as ALLJOBROLES_4, 
coalesce(count(case when CW.MAINJOBROLE = 7 then 1 end), 0) as ALLJOBROLES_7, 
coalesce(count(case when CW.MAINJOBROLE = 8 then 1 end), 0) as ALLJOBROLES_8, 
coalesce(count(case when CW.MAINJOBROLE = 23 then 1 end), 0) as ALLJOBROLES_23, 
coalesce(count(case when CW.MAINJOBROLE = 24 then 1 end), 0) as ALLJOBROLES_24, 
coalesce(count(case when CW.MAINJOBROLE = 25 then 1 end), 0) as ALLJOBROLES_25' 

作爲一個更大的查詢的一部分，我想做的事情上面只有CW.EMPLSTATUS = 1

Answer 1

你可以只添加條件到where條款：

COALESCE(count(case when CW.MAINJOBROLE = 2 and CW.EMPLSTATUS = 1 THEN 1 end),0) as ALLJOBROLES_2, 

順便說一下，COALESCE()應該是不必要的。如果沒有匹配，COUNT()將返回0。

Answer 2

你將不得不圍繞另一個CASE WHEN構造每個表達式：

CASE WHEN CW.EMPLSTATUS = 1 THEN 
    count(case when CW.MAINJOBROLE = 2 THEN 1 end) 
ELSE 
    NULL 
END as ALLJOBROLES_2, 
CASE WHEN CW.EMPLSTATUS = 1 THEN 
    count(case when CW.MAINJOBROLE = 3 THEN 1 end) 
ELSE 
    NULL 
END as ALLJOBROLES_3, 
.... 

Answer 3

我相信你想用SUM（），而不是COUNT（）。

SUM(case when CW.EMPLSTATUS = 1 AND CW.MAINJOBROLE = 2 THEN 1 end) as ALLJOBROLES_2, 
SUM(case when CW.EMPLSTATUS = 1 AND CW.MAINJOBROLE = 3 then 1 end) as ALLJOBROLES_3, 
SUM(case when CW.EMPLSTATUS = 1 AND CW.MAINJOBROLE = 4 then 1 end) as ALLJOBROLES_4, 
SUM(case when CW.EMPLSTATUS = 1 AND CW.MAINJOBROLE = 7 then 1 end) as ALLJOBROLES_7, 
SUM(case when CW.EMPLSTATUS = 1 AND CW.MAINJOBROLE = 8 then 1 end) as ALLJOBROLES_8, 
SUM(case when CW.EMPLSTATUS = 1 AND CW.MAINJOBROLE = 23 then 1 end) as ALLJOBROLES_23, 
SUM(case when CW.EMPLSTATUS = 1 AND CW.MAINJOBROLE = 24 then 1 end) as ALLJOBROLES_24, 
SUM(case when CW.EMPLSTATUS = 1 AND CW.MAINJOBROLE = 25 then 1 end) as ALLJOBROLES_25