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How do you know if a relation is in BCNF?
A relation is in BCNF iff, X is superkey for every functional dependency (FD) X? Y in given relation. In other words, A relation is in BCNF, if and only if, every determinant is a Form (BCNF) candidate key.
How do you know if a relationship is 3NF?
A relation is in 3NF if at least one of the following condition holds in every non-trivial function dependency X –> Y:
- X is a super key.
- Y is a prime attribute (each element of Y is part of some candidate key).
Are the following relations in BCNF 3NF?
The relation is in BCNF. The relation is in 3NF. For 2NF, we go back to our phrase – every non-key attribute depends on the whole key.
In which normal form is the relation R is in?
The relation R is in 1st normal form as a relational DBMS does not allow multi-valued or composite attribute.
What is a BCNF violation?
Informally, a relation is in BCNF if and only if the arrow in every FD is an arrow out of a candidate key. In other words, a relation is in BCNF if and only if the left-hand side of every functional dependency is a candidate key. The left-hand side of C->AF is C, but C is not a candidate key.
How is BCNF calculated?
1 Answer. A relation is in BCNF if and only if each functional dependency X → Y has a determinant ( X ) which is a superkey, that is, it determines all the other attributes of the relation.
Which normal form is best?
Most SQL tutorials and references suggest that you should strive to attain third normal form. Here’s a quick rundown on the first three normal forms: First normal form (1NF) has two requirements: that there be a primary key, and that no column shall contain more than one value.
What is 3NF relation?
The third normal form (3NF) is a normal form used in database normalization. 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.
Which normal form is the best?
So the highest normal form is BCNF.
What is a 3NF violation?
According to the definition of 3NF, you can detect violation of 3NF as follows: Spot/find a functional dependency X → B such that: B is a non-key attribute (i.e., not part of any key), and. X is not a superkey.
What is BCNF normal form example?
Boyce Codd normal form (BCNF) BCNF is the advance version of 3NF. It is stricter than 3NF. A table is in BCNF if every functional dependency X → Y, X is the super key of the table. For BCNF, the table should be in 3NF, and for every FD, LHS is super key.
When is a relation in a 3NF form?
A relation is in 3NF if at least one of the following condition holds in every non-trivial function dependency X –> Y: X is a super key. Y is a prime attribute (each element of Y is part of some candidate key).
When is a relation in third normal form?
A relation is in third normal form, if there is no transitive dependency for non-prime attributes as well as it is in second normal form. A relation is in 3NF if at least one of the following condition holds in every non-trivial function dependency X –> Y: X is a super key. Y is a prime attribute (each element of Y is part of some candidate key).
When to use third normal form ( 3NF )?
X is a super key. Y is a prime attribute (each element of Y is part of some candidate key). A relation that is in First and Second Normal Form and in which no non-primary-key attribute is transitively dependent on the primary key, then it is in Third Normal Form (3NF). Note – If A->B and B->C are two FDs then A->C is called transitive dependency.
Is the relation stud _ no violates the third normal form?
So STUD_COUNTRY is transitively dependent on STUD_NO. It violates the third normal form. To convert it in third normal form, we will decompose the relation STUDENT (STUD_NO, STUD_NAME, STUD_PHONE, STUD_STATE, STUD_COUNTRY_STUD_AGE) as: