数据库中查询的各种连接
?? 表a
表b
?
?左连接 ?select * from a left join b on a.aid=b.bid
?
?
?右连接?select * from a right join b on a.aid=b.bid?
?
?
内连接：select * from a inner join b on a.aid=b.bid?
?
?
?
全连接：select * from a full join b on a.aid=b.bid?
?
交叉连接：select * from a cross join b?
?
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