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 we talk about the relational model in more detail, let us first define some very basic terms used in this model.
Tuple
Every row in a table shows a record and is called a tuple. A table containing 'n' attributes in a record is called n-tuple.
Attribute
The name of every column in a table is used to interpret its meaning and is known as an attribute. Every table is called a relation.
For instance, Figure shows a relation PERSON. The columns NAME, PERSON_ID, AGE and ADDRESS are the attributes of PERSON and every row in the table represents a separate tuple (record).
Relation Name: PERSON
PERSON_ID
NAME
AGE
ADDRESS
TELEPHONE
1
Sanjay Prasad
35
b-4,Modi Nagar
011-25347527
2
Sharad Gupta
30
Pocket 2, Mayur Vihar.
023-12245678
3
Vibhu Datt
36
c-2, New Delhi
033-1601138
Figure: An extended PERSON relation
Deletion Anomalies: Loss of important Information: In some cases, useful information may be lost when a tuple is deleted. For instance, if we delete the tuple corresponding to stu
i want answers this assignment now if yiu can maket for me now ?
Describe the Menu based interfaces for web clients or browsing? Menu-Based Interfaces for Web Clients or Browsing - These interfaces present the user along with lists of option
Mappings between Levels and Data Independence The 3 levels of abstraction in the database do not exist separately of each other. There must be some correspondence, or mapping
Explain what is Aggregation ? Aggregation: This is used whenever we intend to show a relationship between an entity and the relationship. There is no provision for this in th
explain external view
What are the several kinds of the update operations on relations? Also explain the constraints on these update operation. Give instance in support of your answer. There are th
ALTER TABLE Command : This command is used for variation of existing structure of the table in the given situation: When a new column is to be added to the table structure.
Q. Define a weak entity set and its identifying relationship. List the necessary conditions for a meaningful identifying relationship set of a weak entity set. Entity is a t
Birla Institute of Technology & Science, Pilani Work-Integrated Learning Programmes Division Second Semester 2012-2013 EC-1 Assignment 2 (7.5% of the grade) Course No. : SS ZG
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