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Suppose we have a relation R(A,B,C,D,E) with candidate keys {A,B} , {C,D} and let E be a non prime attribute.

If there is a dependency C->E then it is partial dependency as E depends on a part of candidate key {C,D}

Is dependency BC->E partial?

philipxy
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iamkanaramyadav
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    Possible duplicate of [Partial Dependency(Databases)](https://stackoverflow.com/questions/25747802/partial-dependencydatabases) – philipxy Sep 22 '19 at 18:06
  • The definition of partial FD has nothing to do with CKs. Please give your textbook & its definition. It seems like you didn't even find or use the definition of the word you are asking about. Also, what were you able to do applying the definition to BC->E? PS Definitions of 2NF involve partial dependence of non-prime attributes on CKs. – philipxy Sep 22 '19 at 18:12
  • @eponini I just rolled back your edit. The text you code-hilighted is not code, and even if it were, there is no need to highlight the names from code or such tiny fragments of code. Does every SO post need to be in the style you used? Certainly not. So none need to be. An original poster might or might not choose it. Moreover this edit is too trivial for someone without edit permissions. It forces 3 people to look at it for questionable benefit. It should not have been approved. An experienced reviewer rejected it but 2 new reviewers approved it. – philipxy Sep 23 '19 at 04:20

1 Answers1

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A functional dependency is partial if, on removing one or more attributes from the determinant (left-hand side), you still have a dependency that holds. In your example therefore:

{C}→{E} is a full functional dependency

{C,D}→{E} is a partial functional dependency because {C}→{E}

{B,C}→{E} is a partial functional dependency because {C}→{E}

nvogel
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