Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Dependency Preservation
It is obvious that the decomposition must be lossless so that we do not lose any information from the relation that is decomposed. Dependency preservation is another main requirement since a dependency is a constraint on the database. If each attributes appearing on the left and the right side of a dependency appear in the similar relation, then a dependency is considered to be preserved. Therefore, dependency preservation can be checked simply. Dependency preservation is important, because as stated previously, dependency is a constraint on a relation. Therefore, if a constraint is split over more than one relation (dependency is not preserved), the constraint would be complex to meet. We will not talk about this in more detail in this unit. You may refer to the more readings for more details. Though, let us state one basic point:
"A decomposition into 3NF is lossless and dependency preserving whereas a decomposition into BCNF is lossless but may or may not be dependency preserving."
Define Specialisation and generalization in brief? Specialisation / generalization: Generalization or Specialization represents the is a relationship set, an necessary element
What is Multivalued Attribute? Multivalued Attribute - Multivalued attribute might have more than one value for an entity. For instance, PreviousDegrees of a STUDENT.
What is a records management consultation? Our organization is an authority for disseminating your specific requirements and giving you with a solution to effectively manage yo
aggregation
Information about a bank is about customers and their account. Customer has a name, address that consists of house number, area and city, and one or more phone numbers. Account ha
What are the advantages of using a DBMS? The benefits of using a DBMS are a) Controlling redundancy b) Restricting unauthorized access c) Giving multiple user interfac
Explain Alternate key? Alternate Key - All the candidate keys except primary key are known as alternate keys.
Consider the relations City (city_name, state) Hotel (name, address) City_hotel (hotel_name, city_name, owner) Answer the following queries in relational algebra (i) Find
QUESTION (a) Using an appropriate example, explain what is a recursive function? (b) Explain in detail the C++ function given below. void search2(int list[],int n,int ele
Write an sql statement to find what is the percentage of home policies which are from the state of Arizona out of all Home policies by Policy Value.
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd