数据库中查询的各种连接

?? 表a

表b

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?左连接 ?select * from a left join b on a.aid=b.bid

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?右连接?select * from a right join b on a.aid=b.bid?

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内连接：select * from a inner join b on a.aid=b.bid?

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全连接：select * from a full join b on a.aid=b.bid?

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交叉连接：select * from a cross join b?

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