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!
This constraint shows that the key attribute value in each tuple must be unique, i.e., no two tuples have the similar value for the key attribute. This is because the value of the primary key is used to recognize the tuples in the relation.
Example: If A is the key attribute in the following relation R than A1, A2 and A3 must be unique.
A
B
A1
B1
A3
B2
A2
Example: In relation PERSON, PERSON_ID is primary key so PERSON_ID cannot be given as the similar for two persons.
Integrity Constraint
There are two kinds of integrity constraints:
Given the following set of functional dependencies {cf→ bg, g → d, cdg → f, b → de, d → c} defined on R(b,c,d,e,f,g) a. Is cf→ e implied by the FDs? b. Is dg a superkey?
If R1 and R2 are two union compatible relations or functions, then the result of R3 = R1 ∩R2 is the relation that contains all tuples that are in both the relations In other words,
Define Query by Example QBE is a query language relies upon domain calculus and has two dimensional syntax. The queries are written in the horizontal and vertical dimensions of
why are older data base model are being replaced by new data model
Emergence of Client Server Architecture Some of the pioneering work that was completed by some of the relational database vendors permitted the computing to be distributed on m
What are the Overlapping elements Overlapping elements can be found by scanning all the elements in front of deleted element in priority list for the sheet and comparing them
Define Cascading rollback The phenomenon where a single transaction failure leads to a series of transaction rollbacks is known as Cascading rollback.
Eliminate Repeating Groups The problem is, "Find out the list of employees, who knows DB2". For this problem we require to perform an awkward scan of the list looking for re
What is known as clustering file organization? In the clustering file organization, records of several dissimilar relations are stored in the similar file.
One-way Associations If an association is only traversed in single direction, then it is known as one-way association. It is implemented as a pointer or an attribute which con
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