ORACLE JOIN TABLES

Question

我有

T1: USER_ID OSX
       1     Y
       2     Y  

T2: USER_ID ANDROID
       1     Y
       3     Y  

我想按照以下方式加入表格，但我不知道如何

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

Answer 1

您需要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，更好地处理空值：

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