Super Key 1

Question

Consider the following relational schema R(ABCDE). The number of super keys in relation R if every two attributes of relation R is candidate keys are __________.

Please explain a general method to solve

Answer 1

I hope my handwriting is clear enough. 

Comments

Sir in question it says that every two attributes then ok i understood you did 5C2 but why 5C3,5C4 etc. in question it says about every 2 not atleast 2.

Plz Correct me Sir.

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Super keys are superset of candidates key ,in question given that every two attribute is candidate key means you can use two attribute for super key or more than two elements ,so you can select any 2,3,4 or 5.

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Ohk thanku sir

Answer 2

Total super key possible is 26

Answer 3

Other Way to Solve Using Set Theory

R ( A B C D E )

with that 2^5 unique Subset Are possible  but we want only those Subset which Contain  Atleast 2 element then we remove subset with 0 element as well as Subset with 1 element

Subset with 0 element is 1

Subset with Only One Element  is 5C1

ubset which Contain  Atleast 2 element = 32 – 5 – 1

                                                                = 26

CORRECT ME if  i am wrong..