DBMS

DBMS

In DBMS, there could be a question on different steps in normalization and what is achieved at the end of every step in it.You need to be knowing the following things very clearly and without any ambiguity.The question would be based on these terms.

A table is in 1NF if there and no duplicate rows in the table. Each cell is single-valued.

A table is in 2NF if it is in 1NF and if all non-key attributes are dependent on all of the key. A table is in 2NF if it is in 1NF and if it has no partial dependencies

A table is in 3NF if it is in 2NF and if it has no transitive dependencies

A table is in BCNF if it is in 3NF and if every determinant is a candiate key.

A table is in 4NF if it is in BCNF and it it has no multi-valued dependencies.

A table is in 5NF if it is in 4NF and it has no join dependency.

Superkey,Candidate key,Primary key

A superkey is any set of attributes such that the values of the attributes(taken together)uniquely identify one entity in the entity set.

A candidate key is a minimal superkey.

A primary key is one of the candidate keys, designated by the Database designer.