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In relational database if I have two attributes (A and B) which are related by functional dependency A->B. Does this imply that B->A ? In other words if B is dependent on A , is the vice versa true?

Paras Nagpal
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  • Why should it or shouldn't it? Please show some research effort. [ask] [help] – philipxy Oct 14 '20 at 09:25
  • [Is A → B the same as B → A when speaking of functional dependencies?](https://stackoverflow.com/q/44156101/3404097) Please before considering posting read your textbook and/or manual & google any error message or many clear, concise & precise phrasings of your question/problem/goal, with & without your particular strings/names & site:stackoverflow.com & tags; read many answers. Reflect your research. See [ask], other [help] links, hits googling 'stackexchange homework' & the voting arrow mouseover texts. – philipxy Oct 14 '20 at 09:36

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No. Suppose we have a table in database which relates teachers to their subjects. (Teacher->Subject). This does not mean that we can get the name of teacher with the help of subject because multiple teachers can be teaching the same subject. So, this is a many to one mapping.

Ram Bansal
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