Mysql的內連接兩次，使用WHERE上兩個連接

Question

在MySQL中，我想SELECT A.* FROM A其中內加入條件滿足（B加入表）或通過另一種是直接連接表（C），WHERE B.field = myvalue。任何人都可以指出獲得結果的正確方法嗎？

我有以下表格：A，B，C，這是如下關聯（A加入B，B連接C，A加入C）：

 B 
    / \ 
    A --- C 

它看起來很簡單，但我得到當我運行下面的代碼，即使我得到的結果，當我將搜索限制在一個空集，只是到C加入B：

SELECT A.* FROM A 
INNER JOIN C ON C.id = A.c_id 
INNER JOIN B AS B_thru_C ON B_thru_C.id = C.b_id 
INNER JOIN B AS B_from_A ON B_from_A.id = A.b_id 
WHERE B_thru_C.field = 'myvalue' OR B_from_A.field = 'myvalue'; 
# yields an empty set 

SELECT A.* FROM A 
INNER JOIN C ON C.id = A.c_id 
INNER JOIN B AS B_thru_C ON B_thru_C.id = C.b_id 
WHERE B_thru_C.field = 'myvalue'; 
# yields results 

Answer 1

這個怎麼樣？

SELECT A.* FROM A 
LEFT OUTER JOIN C ON C.id = A.c_id 
INNER JOIN B ON B.id = A.b_id OR B.id = C.b_id 
WHERE B.field = 'myvalue';