Jan 8, 2023 · A superkey of a table T is a set of columns that functionally determines every attribute. A candidate key (CK) is a superkey that contains no smaller superkey. We can pick …

Jan 5, 2017 · For a relation R, FD X->Y, holds true for relation R if and only if whenever two tuples of R have the same value of X, they also have the same value for Y. X and Y are a subset of …

May 17, 2013 · superkey: a set of attributes which will uniquely identify each tuple in a relation. candidate key: a minimal superkey. primary key: a chosen candidate key. secondary key: all …

May 9, 2015 · I am trying to find the superkeys of this relation, but I am having troubles finding out how many superkeys there are and exactly what they are. I figured out that the candidate keys …

If I design a database with a securitymaster table that has all the common columns and then have a final column called securitytype which acts as a reference to the sub table, how is it possible to

I got this result by trying out the combinations DA, DB, DC, DE and finding that only DE is the superkey. I'm curious whether my way to directly check if this relation is in BCNF is correct (I …

May 19, 2016 · I'm going though some past papers for my database exam and it asks: Specify all minimal keys for R R(A,B,C,D,E) A → B CD → E E → A B → D I am unsure what is ...

Jan 28, 2015 · The union between A and B is a superkey. (A candidate key is a superkey but a superkey could be not a candidate key) Moreover, remember that a candidate key is a …

Jan 9, 2017 · X is a superkey or; Y is a member of a key. In the second case, since every key in R is simple, Y is itself a key, which implies that X is a superkey. Therefore, X -> Y does not …

A superkey (and therefore a candidate key) that does not contain all attributes must contain at least an attribute set that is the left side of a functional dependency. Otherwise it would not be …