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!
Before defines the second type of integrity constraint, viz., Entity Integrity, we should be well-known with the concept of NULL.
Mostly, NULL is intended as a basis for dealing with the trouble of missing information. This type of situation is frequently encountered in the actual world. For instance, historical records sometimes have entries such as "Date of birth unknown", or police records may contain the entry "Present whereabouts unknown." Therefore it is necessary to have some way of dealing with such concepts in database systems.
Therefore Codd proposed an approach to this issue that creates use of special markers known as NULL to show such missing information.
A given attribute in the relation may or may not be allowed to include NULL. However, can the Primary key or any of its components (in case of the primary key is a composite key) contain a NULL? To answer this Query an Entity Integrity Rule states: No component of the primary key of a relation is permitted to accept NULL. In different words, the definition of each attribute involved in the primary key of any basic relation have to explicitly or implicitly contain the specifications of NULL NOT ALLOWED.
Question: One of the tasks a database management system must perform is to ensure that the data is still intact in the face of software and hardware failure. This task is known
Write the C++ program having class name studentinfo, that is used to store the VU student information: This class should store your VUID, campus id, name and father name in the fol
Define the terms 1) physical schema 2) logical schema. Physical schema: The physical schema explains the database design at the physical level, which is the lowest level of abs
Describe entity referential integrity and integrity. Give an example of each. Entity Integrity Rule - If there is a attribute A of relation R is a prime attribute of R then A
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
Example- Search the salary of employees who are not 'ANALYST' but get a salary below than or equal to any people employed as 'ANALYST'. SELECT EMPNO, ENAME, JOB, SAL FROMEMP
What is relationship instance ? Relationship Instance - A relationship is a relation between two or more entities. An instance of relationship set is a set of relationships.
In object oriented design, which steps must designer take to adjust inheritance? To readjust inheritance following steps should be taken: i) Rearrange and adjust the classe
What is multiplicity in the associations? Give an example to explain multiplicity? Multiplicity in association indicate number of objects participate in any relationship. For
What is SQL Profiler? SQL Profiler is a graphical tool that permits system administrators to monitor events in an instance of Microsoft SQL Server. You can capture and save dat
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