Question

relation FUNDING (city, state, zip, district, budget)

city, state -> zip

zip -> district

state, district -> budget

Which attributes make up the minimal candidate key of the relation FUNDING?

1. City

2. State

3. Zip

4. District

5. Budget

Answer 1

Given dependencies are:

city, state -> zip

zip -> district

state, district -> budget

Lets find the attribute closure first:

city⁺ = city

state+ = state

zip+ = zip,district

district+ = district

budget+ = budget

city,state+ = city,state,zip,district,budget

state,district+ = state,district,budget

All other super keys will be combination of more that 2 attributes.

So minimal combination which can give all the attributes is city,state

So minimal candidate key of relation contains

1.City

2. State