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Oracle内联,外联
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- 2016-06-07 17:08:501186browse
1.内联 a inner join b on a.id=b.id 查两张表都有的id记录。 2.左外联 a left join b on a.id=b.id 只要a表有，而b可没有对应的
1.内联
a inner join b on a.id=b.id
查两张表都有的id记录。
2.左外联
a left join b on a.id=b.id
只要a表有，而b可没有对应的记录。此时b表中的所有字段用null代替。
3.右外联
a right join b on a.id=b.id
和左外联相反，只要b表有，a表可没有对应的记录。
4.全外联
a full join b on a.id=b.id
a表或b表中存在都可。
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