1.在mysql中的使用using,主要用于两个表中有着相同字段查询操作,
与join on中的on操作有着相同功能。
2.以下两个功能结果一样:
select a.title,u.user_name from article as a
join user as u
on a.user_id=u.user_id
select a.title,u.user_name from article as a
join user as u
using(user_id)
1.在mysql中的使用using,主要用于两个表中有着相同字段查询操作,
与join on中的on操作有着相同功能。
2.以下两个功能结果一样:
select a.title,u.user_name from article as a
join user as u
on a.user_id=u.user_id
select a.title,u.user_name from article as a
join user as u
using(user_id)