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What is the difference between 3NF and BCNF?
Boyce-codd normal form(BCNF) was proposed as a simpler form of 3NF,but it was found to be stricter than 3NF,because every relation in BCNF is also in 3NF.However a relation in 3NF is not necessarily in BCNF.
What is the differences between BCNF and 3NF in database?
3NF is where data depends on nothing but the whole key. It seems that every 3NF table should be in BCNF, as BCNF is stricter than 3NF. But, BCNF requires that every nontrivial attribute is a superkey, even if the dependent attributes are part of keys, that is, when X->Y, X is a superkey for the relation, where 3NF also allows that Y is a key attribute for the relation.
Is a relation in bcnf always in 3nf?
Yes.
Why bcnf is stronger than 3nf?
A relation R is in 3NF if and only if every dependency A->B satisfied by R meets at least ONE of the following criteria: 1. A->B is trivial (i.e. B is a subset of A) 2. A is a superkey 3. B is a subset of a candidate key BCNF doesn't permit the third of these options. Therefore BCNF is said to be stronger than 3NF because 3NF permits some dependencies which BCNF does not.
What is overlapping key DBMS?
Overlapping Key is a type of candidate key which occurs in BCNF (Boyce –Codd Normal Form).In the difference between 3NF and BCNF Example : A 3NF table which does not have multiple overlapping candidate keys is guaranteed to be in BCNF. Depending on what its functional dependencies are, a 3NF table with two or more overlapping candidate keys may or may not be in BCNF.
What is Normalization Explain the condition under which a relation needs to be normalized to 3 NF fro3 2 NF with the help of an example?
Define normalization explain the conditions under which a relation need to be normalized to 2nf and 3nf with the help of an example ?
What is the difference between third normal form and bcnf?
Both 3NF and BCNF are normal forms that are used in relational databases to minimize redundancies in tables. In a table that is in the BCNF normal form, for every non-trivial functional dependency of the form A → B, A is a super-key whereas, a table that complies with 3NF should be in the 2NF, and every non-prime attribute should directly depend on every candidate key of that table. BCNF is considered as a stronger normal form than the 3NF and it was developed to capture some of the anomalies that could not be captured by 3NF. Obtaining a table that complies with the BCNF form will require decomposing a table that is in the 3NF. This decomposition will result in additional join operations (or Cartesian products) when executing queries. This will increase the computational time. On the other hand, the tables that comply with BCNF would have fewer redundancies than tables that only comply with 3NF. Furthermore, most of the time, it is possible to obtain a table that comply with 3NF without hindering dependency preservation and lossless joining. But this is not always possible with BCNF.
What is bCnf in rdbms?
It is boyce-codd normal form IN NORMALIZATION WHICH SHOULD BE IN 3NF and EVERY DETERMINAT IS A CANDIDATE KEY .
What are the three primary components of a form in Modern database management?
the three forms of database are in normalization called 1NF, 2NF, and 3NF
What is 3rd normal form in DBMS?
3 NF---------------------------------------- The third normal form (3NF) is a normal form used in database normalization. 3NF was originally defined by E.F. Codd[1] in 1971. Codd's definition states that a table is in 3NF if and only if both of the following conditions hold: * The table is in second normal form (2NF) * No non-prime attribute of the table is transitively dependent on a candidate key A non-prime attribute is an attribute that does not belong to any candidate key. A transitive dependency is a functional dependency X → Z in which Z is not immediately dependent on X, but rather on a third set of attributes Y which depends on X. That is, X → Z by virtue of X → Y and Y → Z. An alternative formulation of Codd's definition, given by Carlo Zaniolo[2] in 1982, is this: a table is in 3NF if and only if, for each of its functional dependencies X → A, at least one of the following conditions holds: * X contains A, or * X is a superkey, or * A is a prime attribute (i.e., A is contained within a candidate key) Zaniolo's definition has the advantage of giving a clear sense of the difference between 3NF and the more stringent Boyce-Codd normal form (BCNF). BCNF simply eliminates the third alternative ("A is a prime attribute"). Example An example of a 2NF table that fails to meet the requirements of 3NF is: Tournament Winners TABLE Tournament Year Winner Winner Date of Birth Indiana Invitational 1998 Al Fredrickson 21 July 1975 Cleveland Open 1999 Bob Albertson 28 September 1968 Des Moines Masters 1999 Al Fredrickson 21 July 1975 Indiana Invitational 1999 Chip Masterson 14 March 1977 The only candidate key is {Tournament, Year}. The breach of 3NF occurs because the non-prime attribute Winner Date of Birth is transitively dependent on {Tournament, Year} via the non-prime attribute Winner. The fact that Winner Date of Birth is functionally dependent on Winner makes the table vulnerable to logical inconsistencies, as there is nothing to stop the same person from being shown with different dates of birth on different records. In order to express the same facts without violating 3NF, it is necessary to split the table into two: Tournament Winners TABLE Tournament Year Winner Indiana Invitational 1998 Al Fredrickson Cleveland Open 1999 Bob Albertson Des Moines Masters 1999 Al Fredrickson Indiana Invitational 1999 Chip Masterson Player Dates of Birth TABLE Player Date of Birth Chip Masterson 14 March 1977 Al Fredrickson 21 July 1975 Bob Albertson 28 September 1968 Update anomalies cannot occur in these tables, which are both in 3NF.
What kind of normal form data does the object-oriented database handle?
BCNF, 3NF, 2NF, 1NF Non First Normal Form Both
What undesirable dependencies are avoided when a relation is in 3NF?
3rd normal form helps reduce redundant data, avoid data anomalies and ensure referential integrity.
