Explain mechanism of nested queries, Database Management System

Assignment Help:

Explain mechanism of nested queries?

SQL gives a mechanism for nesting subqueries. A subquery is a select from where expression that is nested within one more query. A common use of sub queries is to perform tests for set membership, make set comparisons, and verify set cardinality.

a) Set membership

(select customer-name

from depositor)

b) Set comparison

select distinct T.branch-name

from branch as T,branch as S

where T.assets > S.assets and S.branch-city='Brooklyn'

a) Test for Empty Relations

Select customer-name

from borrower

where exits (select *

from depositor

where depositor.customername=borrower.customer-name)

a) Test for the Absence of Duplicate Tuples

 

 


Related Discussions:- Explain mechanism of nested queries

What is normalization, What is normalization? It is a method of analysi...

What is normalization? It is a method of analysing the given relation schemas based on their Functional Dependencies (FDs) and primary key to attain the properties (1).Minim

Create a query to produce single output-er model, This assignment concerns ...

This assignment concerns the Research database. The database ER model is shown above, where attributes are omitted for clarity. The relational model for the database is: Departm

Which sorting technique is used to sort databases, Which sorting technique ...

Which sorting technique is used to sort databases, whose sizes are very big?  Give one such algorithm.  Why do sorting techniques like quicksort, insertion sort, etc.  not applied

Describe models which define the operations on classes, Describe briefly mo...

Describe briefly models which define the operations on classes. The three models which are used to define operations on classes are as: Object Model = data dictionary + Obje

Benefits of using a relational database management system, Question 1: ...

Question 1: a) What is the difference between a non-impact and impact printer? b) Which type of printer is generally used in a supermarket to print your receipt? Describe

Discuss the method for a hash file to expand shrink dynamic, Discuss the me...

Discuss the methods for a hash file to expand and shrink dynamically. What are the advantages and disadvantages of each? The hashing methods that permit dyanamic file expansi

Discuss difference between drop table r and delete from r, Discuss The diff...

Discuss The difference between drop table R and delete from R.  DROP TABLE command deletes all the records with the table definition. This command will automatically committed

Use inheritance as an implementation technique, Use inheritance as an imple...

Use inheritance as an implementation technique when you are going to use inheritance as an implementation technique, you can achieve same goal in a safer way by making one cla

Log, what is the need of a log in dbms

what is the need of a log in dbms

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd