這里為什么不是from users as b呢，不是要從b表中查詢嗎
select b.user_name,b.over,a.over from user1 as a right join user2 as b on a.user_name=b.user_name where a.user_name is not null.
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select b.user_name,b.over,a.over from user1 as a right join user2 as b on a.user_name=b.user_name where a.user_name is not null.
2017-02-28
舉報
2017-02-28
as是給字段起別名，而表的別名直接在原表名后加空格加別名即可