ORACLE連接表

Question

我

T1: USER_ID OSX 
     1  Y 
     2  Y 

T2: USER_ID ANDROID 
     1  Y 
     3  Y 

我想加入的表如下，但我不知道如何

T3: USER_ID ANDROID OSX 
     1  Y  Y 
     2  null  Y 
     3  Y  null 

Answer 1

你想要一個full outer join：

select coalesce(t1.user_id, t2.user_id) as user_id, 
     t2.android, t1.osx 
from t1 full join 
    t2 
    on t1.user_id = t2.user_id; 

Answer 2

使用full join，更好地處理空值：

select coalesce(t1.user_id, t2.user_id) as user_id, 
     coalesce(t2.android,'N/A') as android, 
     coalesce(t1.osx,'N/A') as osx 
from t1 
full join t2 on t1.user_id = t2.user_id