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.
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