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.
Oracle Fusion Middleware: Key Skills: Consulting,Architect, Oracle Fusion Middleware,ECM, UCM, Stellent,Identity Management, SOA Suites, BPEL, ESB,OAM,OIM,J2ee, Java, Livelink
Implementation of association as an object Implement as a separate association object, independent of either class, as in Figure. An association object is a group of pairs
define locking in simple language and decribed it
A video rental company has several branches. The data held on each branch is the branch address made up of street, city, state, and zip code, and the telephone number. Ea
A student entity type has the following attributes,name..
Question : Object-Oriented Database (OODM) is defined as a logical data model that captures the semantics of objects supported in object-oriented programming. An Object-Oriente
Database Errors: An error is said to have occurred if the implementation of a command to manipulate the database cannot be successfully finished either due to inconsistent data or
Consider the relations City (city_name, state) Hotel (name, address) City_hotel (hotel_name, city_name, owner) Answer the following queries in relational algebra (i) Find
When are two schedules said to be view equivalent? Ans: Two schedules that is denoted as S and S' are said to be view equivalent if the subsequent three conditions are met
Un-Normalized Form (UNF) If a table having non-atomic values at every row, it is said to be in UNF. An atomic value is something that cannot be further decomposed. A non-atomic
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