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

Sql select employee from table with at least one department, Consider emplo...

Consider employee (e_no, e_name, e_salary, d_code), dept (d_code, d_name) and dependent (depndt_name, e_no, relation). Show the names of employees in purchase and accounts departm

What is repository?, Problem 1 Why are the operational system keys not ...

Problem 1 Why are the operational system keys not recommended for forming data warehouse primary keys? Give any two examples 2 Explain the following performance tuning techn

Project on designing and creating a database , This project will involve de...

This project will involve designing and creating a database for an organization.  In the design of a database, there is no single "perfect" design.  So your database design may not

#title using the invoice, using the invoice table shown below,write the rel...

using the invoice table shown below,write the relational schema,draw a dependencies,inclunding all partial and transitive dependencies.assume that the table does not contain repeat

Explain foreign key, Explain Foreign Key? Foreign Key - Let there are...

Explain Foreign Key? Foreign Key - Let there are two relations (tables) R and S. Any candidate key of the relation R that is referred within the relation S is known as the fo

What is alternate key, What is Alternate Key Alternate Key: This is t...

What is Alternate Key Alternate Key: This is the candidate key which is not taken as the primary key of the table. They are named so because although not the primary key, the

Discuss the term- design optimization, Discuss the term- Design Optimizatio...

Discuss the term- Design Optimization  We have seen various ways of representing the objects.The fundamental design model uses analysis model as the framework for implementati

What is a disjoint less constraint, What is a disjoint less constraint? ...

What is a disjoint less constraint? Ans: It needs that an entity belongs to no much more than one level entity set.  Disjoint less constraint needs that an entity belongs to

Need point of sale software for pizza restaurant, Project Description: N...

Project Description: Need Point of Sale software for pizza restaurant. Delivery and take out service, client's database, inventory control, order history, last order, order from

State about the activity diagram, State about the Activity Diagram Act...

State about the Activity Diagram Activity diagrams show flow from one activity to other. It is an ongoing non atomic execution within a state machine. Activity finally results

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