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.
What is a Linked Server? Linked Servers is a method in SQL Server by which we can add other SQL Server to a Group and query both the SQL Server dbs using T-SQL Statements. With
Define single valued and multivalued attributes. Single valued attributes: attributes with a single value for a particular entity are known as single valued attributes. Mult
The technique of converting the state diagram to code a) Identify all major control paths. Start from initial state; choose a path across the diagram that corresponds to normal
Differance between DDL and SDL? DDL and SDL - The data definition language (DDL) is used through DBA and database designers to describe internal schema, conceptual schema, and
What is E-R model? This data model is based on real world that having of basic objects called entities and of relationship between these objects. Entities are explained in a da
What's the difference between a primary key and a unique key? Both primary key and unique key enforces uniqueness of the column on which they are explained. But by default prim
What are the ways of obtaining the connection parameters? Hardwire the parameters into the program. Ask for the parameters interactively. Get the parameters
a. Define the term "deadlock". There are four conditions that must hold before deadlock is possible. Name them. b. Outline an algorithm that detects whether there is a deadlock.
What is the main advantage of the object model? What are its different components? The object model focuses on the logical data structures. Each object model comprises of many
Give the general form of SQL query? Select A1, A2............., An From R1, R2..............., Rm Where P
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