What is nested queries explain in details, Database Management System

Assignment Help:

What is Nested Queries explain in details?

Nested Queries - A SELECT query could have subquery(s) in it. While a SELECT query having another SELECT query in it, is known as nested query. A few operations cannot be performed along with single SELECT command or along with join operation. There are some operations that can be performed along with the help of nested queries (also referred to as subqueries). For instance, we want to calculate the second highest salary:

SELECT MAX(SAL) FROM EMP WHERE SAL < (SELECT MAX(SAL) FROM EMP)

Some operations can be performed both through Join and subqueries. The Join operation is costlier in terms of space and time. Thus, the solution based on subqueries is preferred.


Related Discussions:- What is nested queries explain in details

Explain nested relations, Explain nested relations? Nested relations ...

Explain nested relations? Nested relations The assumption of INF is a natural one in the bank examples we have considered. However, not all applications are best modelled

Draw an entity-relationship model, Draw an Entity-Relationship model for ...

Draw an Entity-Relationship model for the relational schema given in the Appendix. Show all the entities, relationships, relationship names, and attributes and also underline the

Give an example of operations from the functions of a bank, Give an example...

Give an example of Operations from the functions of a bank. For creation of a saving account, you can write: bank::: create -savings-account (customer)->account. For oper

Explain data models namely relational network - hierarchical, Explain the t...

Explain the three data models namely relational, network and hierarchical and evaluate their relative advantages and disadvantages. Hierarchical Model: In hierarchical model, da

E-commerce and business intelligence systems., Your friend owns and operate...

Your friend owns and operates a wholesale shoe business with annual revenues of $5 million dollars. His wholesale business specializes in supplying and supporting retailers with sh

Fire dementpart, The State of NewYork certifies firefighters throughout sta...

The State of NewYork certifies firefighters throughout state and keep track all of them, as well as of the state’s fire departments. Each fire department has unique department numb

Sql, Events4Fun is an event management company in Europe with branches in S...

Events4Fun is an event management company in Europe with branches in South America as well. The company is well-known for its efficiency, good-quality services, and affordable char

Explain data dictonary on oracle, Explain data dictonary on oracle ? Da...

Explain data dictonary on oracle ? Data Dictionary - Data dictionaries are the system tables in which contain descriptions of the database objects and how they are structured.

Design an algorithm to implement operations, Design an algorithm to impleme...

Design an algorithm to implement operations  Each and every operation specified in the functional model could be formulated as an algorithm. The algorithm indicates how operat

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