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In which two cases would you use an outer join? （）
A:The tables being joined have NOT NULL columns.
B:The tables being joined have only matched data.
C:The columns being joined have NULL values.
D:The tables being joined have only unmatched data.
E:The tables being joined have both matched and unmatched data.
F:Only when the tables have a primary key/foreign key relationship.

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出自：Oracle认证

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