Suppose the schema Widgets area brightness changeability de

Suppose the schema Widgets = {area, brightness, changeability, density, energy} has the FD\'s

e->a
cd->e
a->b

What is the highest normal form the schema is in? Explain.

Further, give a scenario for an insert anomaly caused by this low NF.

Solution

Steps for finding the highest normal form of a relation

STEP 1 : Candidate key -> (c,d)

STEP 2: Prime Attributes ->(c,d) ; Non-Prime attributes -> (a,b,e)

STEP 3: It\'s in first normal form as it doesn\'t have any multivalued attributes. It\'s in the 2nd normal as every non-prime attributes hold a full functional dependency with all prime attributes. It\'s not in the 3rd normal form as transitive dependency holds.

Therefore the given schema is in 2NF(i.e. 2nd Normal Form) .

Insert anomaly:

During insertion of a tuple which has the same value for the attribute, \'energy\', each time we have to enter the corresponding value of the attribute, \'area\', and similarly for the same value of the attribute, \'area\' we have to enter the corresponding value of the attribute, \'brightness\' each time.