兩個表(family_table)
和(children_table)
由family_id
相關, 你怎麼指望有state 'a'
和孩子經由一個查詢有state 'b'
到每個家庭的孩子嗎?兩個值在左外算上加盟同桌
我試過的children_state 'a'
查詢但children_state 'b'
計數的結果,計數是錯誤的,我不知道問題出在哪裏,我的查詢是:
select f.family_id ,
count(c.family_id) as [B children Count] ,
count(cp.family_id) as [A children Count]
FROM Family_table as f left outer join children_table as c
on c.family_id = f.family_id and c.children_state = 'B' left outer join children_table as cp
on cp.family_id = f.family_id and c.children_state = 'A'
確定..如果我想指望有狀態的孩子什麼'A'和沒有說明'A'或'c'的孩子? – Hamonbatra
@ user3038625您對c.children_state的約束可以在group by之前添加。關鍵的一點是,一旦約束得到滿足,小組將會爲你做點數。例如('A','B')中的c.children_state和('A','B')或(c.children_state ='C'和c.children_state!='A')中的c.children_state替換和c.children_state –
對不起,但結果是錯誤的 – Hamonbatra