If a proper subset of X is a superkey, then X cannot be a key.Question 4Select one:TrueFalse
Question
If a proper subset of X is a superkey, then X cannot be a key.Question 4Select one:TrueFalse
Solution
False
Explanation: A superkey is a set of attributes of a relation schema upon which all attributes of the schema are functionally dependent. No proper subset of a superkey can be a superkey. However, X can still be a key even if a proper subset of X is a superkey. A key is a minimal superkey, meaning it is a superkey such that no proper subset of it is also a superkey. So, if X is a key, no proper subset of X can be a superkey. But if a proper subset of X is a superkey, X can still be a key if it is minimal.
Similar Questions
A Superkey is:
A Superkey is:Select one:a.Every superkey is a primary keyb.A superkey is an attribute or a set of attributes that can uniquely identify a tuplec.A superkey is a tuple or a set of tuples that can uniquely identify an attributed.Every superkey is a candidate key
______________ is the superset of all keys in a relation.
Which of the following below statement is true?a.Super key attribute set ⊂ candidate key attribute setb.Super key attribute set ⊃ candidate key attribute setc.Super key attribute set ⊇ candidate key attribute setd.Super key attribute set ⊄ candidate key attribute set
Which of the following statements are TRUE?All superkeys are candidate keysAll candidate keys are superkeysA foreign key can be a primary keyAll superkeys are primary key
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.