OCP-1Z0-051-题目解析-第9题

9. Which statement is true regarding the INTERSECT operator?

A. It ignores NULL values.

B. Reversing the order of the intersected tables alters the result.

C. The names of columns in all SELECT statements must be identical.

D. The number of columns and data   types must be identical for all SELECT statements in the query.

Answer: D

题目解析：关于交集操作。以下哪个说法是正确的？

A：交集操作忽略Null （错误。交集操作不会忽略空值）

B: 交换两个表的顺序。交集的结果会不同（错误。交集的结果与表的顺序无关）

C: 在全部的Select语句中。字段的名称必须同样（错误，字段的名称能够不同。但字段的数量和数据类型必须一致）

D: 在全部的Select语句中，字段的数量和数据类型必须同样（正确）。

时间： 2024-10-05 01:34:37

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