问答题

什么是实体完整性规则？

答案：正确答案：实体完整性是指对关系中的每一个元组，其主键属性对应的各个分量不能为空值

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Which of the following is always true about capital rationing?
1 The profitability index is suitable for handling multiple-period capital rationing problems if projects are divisible.
2 Projects being divisible is an unrealistic assumption. A.
1、true 2.false B.
1、false 2、false C.
1、true 2、true D.
1、false 2、true