2
votes
"Functional dependencies" with cardinality constraints
After searching around for paper some more (unfortunately, I found nothing in Ling Liu, M. Tamer Özsu eds. Encyclopedia of Database Systems), I managed to find out that these dependencies are called ...
- 171
1
vote
Accepted
Find number of candidate keys given non-trivial functional dependency X->Y, where X is some set of attributes and Y is some prime attribute
X -> Y non-trivial means that X does not include Y. Since ...
- 809
1
vote
Functional dependencies on relational schema
I assume, by key, you mean the candidate key.
Let's check whether V is a candidate key:
closure(V) = {V, W, X, Y, Z}
Hence, V is a candidate key.
closure(W) = {W, V, X, Y, Z}
Hence, W is also a ...
1
vote
Accepted
Normal form after decomposition of a relation
I think you are wrong.
Here is a rough sketch of a proof (by contradiction) that the original claim is true.
Suppose that the claim is false: this means that R1 or R2 (or both) are not
in 3NF. ...
- 809
1
vote
Functional Dependencies
$R$ has only five non-trivial functional dependencies (FDs).
No, $R$ has many more non-trivial FDs. For example, Since A-> BC and C -> F, we also have AC->BF, which is also a non-trivial FD ...
- 39.1k
1
vote
Accepted
Given a relation and asked to enumerate all FD's and mark the trivial FD's
I suppose that in the exercise, the request “organize them accordingly to the LHS”, is just a request of sorting all the functional dependencies (maybe lexicographically) with respect first to the ...
- 809
Only top scored, non community-wiki answers of a minimum length are eligible