该表是否规范化为2NF?

时间:2018-09-11 18:41:52

标签: database relational-database database-normalization

我正在研究归一化,想知道是否可以将此表归一化为2NF?

FishTable

1 个答案:

答案 0 :(得分:0)

是的,是:

1NF: A relation is in first normal form if and only if the domain of each attribute contains only atomic (indivisible) values, and the value of each attribute contains only a single value from that domain.

由于湖泊/克里克的名字虽然包含了鱼类的名字,但不可分割,因此它们本身就是原子的。

换句话说:仅湖泊/克里克名称的第一个单词不足以正确识别湖泊/克里克,第二个单词也是如此。

2NF: [...] a relation is in 2NF if it is in 1NF and no non-prime attribute is dependent on any proper subset of any candidate key of the relation. A non-prime attribute of a relation is an attribute that is not a part of any candidate key of the relation.

PK属性 Fish 没有适当的子集,因为它只是一个(除了空集{},请参见注释)。 Best Lake 是非素数,因为它不属于PK,并且不依赖于子集(,因为除了空子集之外,没有合适的子集 ),但总体而言。