Prove that a relation which is 4nf must be bcnf, Database Management System

Assignment Help:

Prove that a relation which is 4NF must be BCNF.  

Ans Let R be in 4NF.  Suppose it is not in BCNF.  Hence, there exists an FD X→Y in R such that x is not a super key. Although by the rule M1 X→Y|=x→→Y. Once again x here is not a super key.  This contradicts the fact that R is in 4NF.  Hence, our assumption is false.  Each R in 4NF should be in BCNF.


Related Discussions:- Prove that a relation which is 4nf must be bcnf

Failure controlling methods, Failure Controlling Methods: Failures can be h...

Failure Controlling Methods: Failures can be handled using different recovery methods that are talk about later in the unit. But the first question is doing we really require recov

How nulls are treated in comparison operator, How nulls are treated in comp...

How nulls are treated in comparison operator? Along with comparison (relational) operators, the null values are ignored as we cannot derive the relation along with the given op

Create a view containing name and number of department, Create a view emp_d...

Create a view emp_dep containing e_name and number of dependents from the tables employee and dependent of (i) CREATE VIEW emp_dept AS SELECT ename, COUNT(*) FROM employee, dep

Define the boyce-codd normal form, Define the Boyce-Codd Normal Form with i...

Define the Boyce-Codd Normal Form with instance and also Compare BCNF and 3NF.  Ans: BCNF: For each functional dependency X->Y in a set F of functional dependencies over relati

Unit database integrity, Relations create the database. They must satisfy v...

Relations create the database. They must satisfy various properties, like no duplicate tuples, no ordering of tuples, and atomic attributes, etc. Relations that satisfy these basic

Describe integrity constraints, Describe integrity constraints? Integr...

Describe integrity constraints? Integrity Constraints - A database is just as excellent as the information stored in it, and a DBMS must therefore help avoid the entry of inc

What is a security, What is a security? Securities are claims on financ...

What is a security? Securities are claims on financial assets.  They can be illustrated as "claim checks" which give their owners the right to receive funds in the future.  Sec

What is the use of unique function, What is the use of unique function? ...

What is the use of unique function? UNIQUE function: If UNIQUE is specified then only unique values are used to computed the mean.

What are the properties in a relation, What are the properties in a relatio...

What are the properties in a relation ? In a relation Ordering of rows is immaterial and No two rows are identical.

When are they useful justify with an example, When are they useful? Justify...

When are they useful? Justify with an example. The temporary tables are commonly used to support specialized rollups or exact application processing needs. Unlike a permanent t

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd