The difference between 2NF and BCNF

According to the wikipedia example, the following example is not bcnf because there are overlapping candidate keys (name and job, name and contractor)

Name   Work        Contractor
John   Plumber     Plumber industries
Ryan   Plumber     Plumber industries
Ryan   Elektrician Electro industries

However, is this table also not in 2NF? Keep in mind that the name and work constitute the primary key, the contractor can only be obtained from the work, why should the database be divided?

If my statement is true, can someone provide me with a (easy) example of a database that is not in BCNF but is 2NF?

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2 answers

Is this table also not in 2NF?

, 2NF. 2NF , nonprime -. nonprime, 2NF. BCNF 2NF/3NF. BCNF , . 2NF 3NF .

nonprime , - -.

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2NF. -. . , . , prime/key. , .

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Source: https://habr.com/ru/post/1523500/


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