View stunning SlideShares in full-screen with the new iOS app!Introducing SlideShare for AndroidExplore all your favorite topics in the SlideShare appGet the SlideShare app to Save for Later — even offline
View stunning SlideShares in full-screen with the new Android app!View stunning SlideShares in full-screen with the new iOS app!
If I know just Description, can I find out Supplier Address? No,
because we have more than one supplier for the same product.
If I know just Supplier, and I find out Supplier Address? Yes.
The Address does not depend upon the description of the item.
Therefore, Supplier Address is NOT functionally dependent upon the ENTIRE PK (Description-Supplier)
for its existence.
Supplier Address Name Supplier Supplier Address Cost Supplier Description Inventory
So putting things together The above relation is now in 2NF since the relation has no non-key attributes. Supplier Address Cost Supplier Description Inventory Cost Supplier Description Inventory Supplier Address Name Supplier
3) Remove columns that are not dependent upon the primary key. So for every nontrivial functional dependency X --> A, (1) X is a superkey, or (2) A is a prime (key) attribute.
S(SUPP#, PART#, SNAME, QUANTITY) with the following assumptions:
(1) SUPP# is unique for every supplier. (2) SNAME is unique for every supplier. (3) QUANTITY is the accumulated quantities of a part supplied by a supplier. (4) A supplier can supply more than one part. (5) A part can be supplied by more than one supplier.
We can find the following nontrivial functional dependencies:
Second Normal Form: Each column must depend on the *entire* primary key.
Third Normal Form: Each column must depend on *directly* on the primary key.
Boyce-Codd Normal Form (BCNF) Boyce-Codd normal form (BCNF) A relation is in BCNF, if and only if, every determinant is a candidate key. The difference between 3NF and BCNF is that for a functional dependency A B, 3NF allows this dependency in a relation if B is a primary-key attribute and A is not a candidate key, whereas BCNF insists that for this dependency to remain in a relation, A must be a candidate key.