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Is it possible that a relation be in 3NF but not in 2NF?
Yes, Korth’s definition for 3NF implies 2NF. The candidate key here is {pub_id, auth_id} . Obviously, this relation is not in 2NF because publisher_name is dependent on pub_id , which is a subset of the candidate key (therefore it is not fully functionally dependent on the only candidate key).
Can 2NF and 3NF be the same?
A relation R having functional dependency A–>B is in 3NF if either of the conditions given below are true . A is a superkey. B is prime attribute, that is B is the part of candidate key….Difference between 2NF and 3NF :
| S.NO. | 2NF(Second Normal Form) | 3NF(Third Normal Form) |
|---|---|---|
| 1. | It is already in 1NF. | It is already in 1NF as well as in 2NF also. |
What are the conditions to be satisfied for a relation to be in 2NF and 3NF?
Codd’s definition states that a table is in 3NF if and only if both of the following conditions hold: The relation R (table) is in second normal form (2NF). Every non-prime attribute of R is non-transitively dependent on every key of R.
What is the difference between 2nd and 3rd normal form?
A relation is in second normal form if it is in 1NF and every non-key attribute is fully functionally dependent on the primary key. A relation is in third normal form if it is in 2NF and there are no dependencies between non-key attributes. (i.e. 2NF + no transitive dependencies).
When does a relation be in 1NF or 2NF?
Normal Form Description; 1NF: A relation is in 1NF if it contains an atomic value. 2NF: A relation will be in 2NF if it is in 1NF and all non-key attributes are fully functional dependent on the primary key. 3NF: A relation will be in 3NF if it is in 2NF and no transition dependency exists. 4NF
What’s the difference between 2NF and 3NF in DBMS?
So AB is a candidate key. The relation R is in 1NF as relational DBMS does not allow multi-valued or composite attribute. The relation R is in 2NF as no prime attribute is deriving non prime attibute that is there is no partial functional dependency. The relation R is not in 3NF as non-prime attribute is deriving non-prime attribute.
When to use 1NF or 2NF in normalization?
Normalization divides the larger table into the smaller table and links them using relationship. The normal form is used to reduce redundancy from the database table. A relation is in 1NF if it contains an atomic value. A relation will be in 2NF if it is in 1NF and all non-key attributes are fully functional dependent on the primary key.
How are non prime attributes different in 2NF and 3NF?
In 2NF non-prime attributes are allowed to be functionally dependent on non-prime attributes. In 3NF non-prime attributes are only allowed to be functionally dependent on Super key of relation. 3. No partial functional dependency of non-prime attributes are on any proper subset of candidate key is allowed.