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.
Synonyms and Indexes Some of the essential properties of indexes are: An Index is a schema Object Indexes can be formed explicitly or automatically Indexes are m
What are the purpose for having variable length records? What kinds of separator characters are required for each? Variable-Length Records - Variable-length records are thos
Importance Of File Organisation In Database To execute a database efficiently, there are various design tradeoffs needed. One of the most vital ones is the file Organisation. F
what is cascading? what is rollback cascading? please explain in detail
Describe the advantage of State chart Diagram A state chart represents a state machine, emphasizing flow of control from one state to other. A state machine is a behaviour whi
3 assignments combined in 1
What are the two methods for dealing deadlock problem? The two procedures for dealing deadlock problem is deadlock detection and deadlock recovery.
Explain Candidate Key and Super Key A super key is a set of one or more than attributes that, taken collectively, permits us to identify uniquely a tuple in the relation. Wher
Make SQL statements for the following scenarios. Your response should contain SQL statement, output and any other assumptions you have made to arrive at the answer. For Colorado cu
In an organisation various projects are undertaken. Each projects can employ one or more employees. Every employee can work on one or more projects. Each project is undertaken on
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