Multiple choice

Consider the following relational schema:

Suppliers(sid:integer, sname:string, city:string, street:string) Parts(pid:integer, pname:string, color:string) Catalog(sid:integer, pid:integer, cost:real) Assume that in the suppliers relation above, each supplier and each street within a city has a unique name, and (sname, city) forms a candidate key. No other functional dependency is implied other than those implied by primary and candidate keys.

Which of the following statements is TRUE about the above schema?

  1. The schema is in BCNF.

  2. The schema is in 3NF, but not in BCNF.

  3. The schema is in 2NF, but not in 3NF.

  4. The schema is not in 2NF.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 The schema is in 3NF, but not in BCNF. (sname, city) forms the candidate key.
Suppliers(sid, sname, city, street)
sname is primary key.
sid, sname is also key.
city--> street
street is functionally dependent upon city.
sname--> city
So, transitivity occurs.
So, the schema is in 3NF, but not in BCNF.

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