left outer join和left join有区别?

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left outer join和left join有区别?

left outer join和left join有区别?
left outer join和left join有区别?

left outer join和left join有区别?
left join 是 left outer join 简写
以下是例子
a表:f1 f2 f3 b表:f4 f5 f6 f7
1 2 3 1 1 1 1
4 5 6
select a.* ,b.* from a a left outer join b b on a.f1 = b.f4
结果:f1 f2 f3 f4 f5 f6 f7
1 2 3 1 1 1 1
4 5 6
结果同使用left join 一样