The Relation Vendor Order (V_no, V_ord_no, V_name, Qty_sup, unit_price) is in…
2015
The Relation
Vendor Order (V_no, V_ord_no, V_name, Qty_sup, unit_price)
is in 2NF because :
- A.
Non_key attribute V_name is dependent on V_no which is part of composite key
- B.
Non_key attribute V_name is dependent on Qty_sup
- C.
Key attribute Qty_sup is dependent on primary key unit_price
- D.
Key attribute V_ord_no is dependent on primary key unit_price
Attempted by 388 students.
Show answer & explanation
Correct answer: A
Note:- The Question is ambiguous and was dropped by Examination authority.
Short answer: The relation is NOT in Second Normal Form (2NF).
Reason: Assume the primary key is the composite (V_no, V_ord_no). The attribute V_name depends only on V_no, which is a part of the composite key. This is a partial dependency of a non-key attribute on part of the primary key, which violates 2NF.
How to fix (decomposition):
Create Vendor(V_no, V_name) where V_no is the primary key and V_name depends on the whole key.
Create VendorOrder(V_no, V_ord_no, Qty_sup, unit_price) with composite primary key (V_no, V_ord_no).
Result: After decomposition there are no partial dependencies of non-key attributes on part of a composite key, so each resulting relation satisfies 2NF.
Note: The statement that 'Non_key attribute V_name is dependent on V_no' correctly identifies the partial dependency problem; it does not justify that the original relation is in 2NF.