DBMS Basics - Interview Questions and Answers
What is Lossless join property?
It guarantees that the spurious tuple generation does not occur with respect to relation schemas after decomposition.
What is 1 NF (Normal Form)?
The domain of attribute must include only atomic (simple, indivisible) values.
What is Fully Functional dependency?
It is based on concept of full functional dependency. A functional dependency X Y is full functional dependency if removal of any attribute A from X means that the dependency does not hold any more.
What is 2NF?
A relation schema R is in 2NF if it is in 1NF and every non-prime attribute A in R is fully functionally dependent on primary key.
What is 3NF?
A relation schema R is in 3NF if it is in 2NF and for every FD X A either of the following is true
- X is a Super-key of R.
- A is a prime attribute of R.
In other words, if every non prime attribute is non-transitively dependent on primary key.
What is BCNF (Boyce-Codd Normal Form)?
A relation schema R is in BCNF if it is in 3NF and satisfies an additional constraint that for every FD X A, X must be a candidate key.