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mysql lEFt out join

无区别left join 是left outer join的简写,left join默认是outer属性的。

mysql不支持full join,完全连接。支持左连(left join),右连(right join)和内连(inner join) 要想达到full join的作用,必须使用left join + union(不能是union all)+right join SELECT * FROM ( SELECT * FROM select_in a LEFT JOIN select_o...

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