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!
Relations create the database. They must satisfy various properties, like no duplicate tuples, no ordering of tuples, and atomic attributes, etc. Relations that satisfy these basic needs may still have some undesirable characteristics such as data redundancy, and anomalies.
What are these undesirable characteristics and how can we eliminate them from the database system? This part is an attempt to answer this question. Though, please note that most of these undesirable properties do not arise if the database modelling has been carried out very carefully using some method like the Entity-Relationship Model. It is still important to use the methods in this unit to check the database that has been acquired and ensure that no mistakes have been made in modeling.
The central thought in these discussions is the concept of Database integrity, the notion of functional dependency, which rely on understanding the semantics of the data and which deals with what information in a relation is dependent on what other information in the relation. Our prime objective in this section is to describe the concept of data integrity, functional dependence and then describes normal forms using functional dependencies and using other types of data dependencies.
OBJECTIVES
After reading this section you should be able to
a publishing company produce scientific books on various subjects. the books are written by authors who specialize in one particular subject. the company employs editors who, not n
Project Description: My VBulletin forum was hacked, and soon after my server machine died. So, I'm now on a new machine, and I think that I've taken care of 99% of the hacking..
Construct a clean ans concise ER diagram for the database indicating the cardinality mapping for Employee management syatem
Gaps in sequence values can happen when: - A rollback happens that is when a statement changes are not accepted. - When the system crashes - When a sequence i
What are deadlocks? How can they be avoided? Ans: Deadlock considers to a particular condition when two or more processes are every waiting for another to release a resource,
What is inheritance? Inheritance is an object orientation concept that allows reusability of code / design. Basic sense of inheritance is that if one class is predefined than a
Example RELATION SCHEMA for STUDENT: STUDENT (Roll No: string, name: string, login: string, age: integer) RELATION INSTANCE
Which element in the database can modified by changing the data dictionary? Data elements in the database can be changed or modified through changing the data dictionary.
Advantages of Database management system Let us summarize the advantages. Reduction of Redundancy: This is perhaps the most important advantage of using DBMS. Redundancy i
What are stand-alone procedures? Procedures that are not part of a package are called as stand-alone because they independently defined. A good example of a stand-alone procedu
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