给定关系R（A，B，C，D）和关系S（A，C，D，E，F），对其进行自然连接运算RS后的属性列为（ ）个。
- A.5
- B.6
- C.8
- D.9
正确答案及解析
正确答案
解析
自然连接（Natural join）是一种特殊的等值连接，它要求两个关系中进行比较的分量必须是相同的属性组，并且在结果中把重复的属性列去掉。所以这里自然连接去掉了重复的A、C、D列，保留了A、B、C、D、E、F共6个列，B选项正确。
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