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Which two statements are true about a self join?

2020.2.1 071 99

(关于自连接,哪两个陈述是正确的?)

A The join key column must have an index.(连接键列必须具有索引。)

B It can be a left outer join. (它可以是左外部联接。)

C It must be a full outer join. (它必须是完整的外部联接。)

D It can be an inner join. (它可以是内部联接。)

E It must be an equijoin.(它必须是等分的)

答案:BD

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