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!
In a relation, tuples are not inserted in any definite order. Ordering of tuples is not defined as a part of a relation definition. Though, records may be structured later according to some attribute value in the storage systems. For instance, records in PERSON table may be structured according to PERSON_ID. Such organisation or data depends on the requirement of the underlying database application. Though, for the purpose of display we may get them displayed in the sorted order of age. The following table is sorted by age. It is also worth states here that relational model does not permit duplicate tuples
PERSON
PERSON_ID NAME AGE ADDRESS
2 Sharad Gupta 33 Pocket 2, Mayur Vihar.
1 Sanjay Prasad 35 b-4,Modi Nagar
3 Vibhu Datt 36 c-2, New Delhi
Super Keys, Candidate Keys and Primary Keys for the Relations
As discussed in the last section ordering of relations does not matter and all tuples in a relation are unique. Though, can we uniquely recognize a tuple in a relation? Let us talk about the concepts of keys that are primarily used for the purpose as above.
What are shortcomings in structured approach? Structured methodology treats data and their behaviours separately, and this makes it harder to isolate changes. If changes are re
Explain the disadvantages of file oriented approach? In the oriented approach Applications are designed in isolation. Design of application is optimized for one application. In
What are the categories of SQL command? SQL commands are separated in to the following categories: 1. Data - Definitition Language 2. Data Manipulation language 3. Dat
Explain Relational model and their use in DBMS? Relational Model - The relational model was first introduced through E.F. Codd of the IBM Research in the year of 1970. The mode
Describe the statement in SQL which allows to change the definition of a table? In SQL Alter statement is used to allow the changes the definition of a table.
data models are being replaced over years. Reasons and why does that happen?
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
Foreign Keys and NULL Let us take the relation: DEPT DEPT ID DNAME BUDGET D1 M
Benefits: It limits data access. It makes difficult queries look easy. It permits data independence. It presents dissimilar views of the similar data.
Explain natural join? Natural Join - Similar as equi-join except in which the join attributes (having similar names) are not involved in the resulting relation. Only one sets
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