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!
Security: Data not needed by local applications is not stored at the site, therefore no unnecessary security violations may exist.
But how can we carry out fragmentation? Fragmentation may be carried out as per the following rules:
a) Completeness: This rule makes sure that there is no loss of data while fragmentation. If a relation is decomposed into fragments, then every data item must appear in at least single fragment.
b) Reconstruction: This rule makes sure preservation of functional dependencies. It should be possible to describe a relational operation that will reconstruct the relation from its fragments.
c) Disjointness: A data item that shows in a fragment should not show in any other fragment. Though, a typical fragmentation known as vertical fragmentation is an exception to this rule. In vertical fragmentation the primary key attributes must be repeated to permit reconstruction of original relation.
This rule makes sure minimization of data redundancy. What are the dissimilar types of fragmentation?
Can a domain, assigned to a data element be changed? Yes. We can do so by just overwriting the entry in the field domain.
how to prepare a data dictionary for online examination system for certified courses?
What is meant by functional dependencies? Consider a relation schema R and α C R and β C R. The functional dependency α ->β holds on relational schema R if in any legal relati
Rules Of Data Normalisation Let us now summarise Normalisation with the help of various clean rules. The following are the necessary rules for the Normalisation process: 1.
Which operator is used to compare a value to a list of literals values that have been specified? BETWEEN operator is used to compare a value to a list of literals values that h
Define Boyce codd normal form A relation schema R is in BCNF with respect to a set F of functional dependencies if, for all functional dependencies in F + of the form.α ->β.
Given the subsequent relations: vehicle (reg_no, make, colour) Person (eno, name, address) Owner (eno, reg_no) Write expressions
SELECT Statement This statement is used for retrieving information from the databases. It can be coupled with many clauses. Let us talk about these clauses in more detail:
Benefits of heap files 1. This is a easy file Organisation method. 2. Insertion is somehow capable. 3. Good for bulk-loading data into a table. 4. Best if file
Why do so various organizations use MySQL? Advantages: Open source Highly efficient Offers a high scalability in terms of size and connectivity. Highly prote
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