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databasedatabase-designfunctional-dependencies

Calculate candidate keys given functional dependencies

I have a relation with the following functional dependencies :

A  -> B
AC -> D
EF -> AG
AG -> H

the couple (EG) is unique.

I want to calculate the candidate keys, should i add a functional dependency from the unique couple ?

Solution

  • You should absolutely add the FD EG->ABCDFH. If you don't you'll never determine that EG is a candidate key. That is, you can't derive EG as a candidate key from the four FDs you've explicitly listed.