Self-join, Database Management System

Assignment Help:

Self-Join:  In a self join a table is joined with itself.  Let consider the following sample partial data of EMP table

EMPNO

ENAME

MGRID

.....

1

Nirmal

4

 

2

Kailash

4

 

3

Veena

1

 

4

Boss

NULL

 

.....

.....

...

 

Example: Search the name of each employee's manager name.

SELECT WORKER.ENAME || 'WORK FOR' || MANAGER.ENAME FROM EMP WORKER, EMP MANAGER

WHERE WORKER.MGR=MANAGER.EMPNO;

Output:

                                                                        2033_Self-Join.png


Related Discussions:- Self-join

What are composite objects, What are composite objects? Objects that ha...

What are composite objects? Objects that have other objects are known as complex objects or composite objects.

Define partial, Partial Key : It is a group of attributes that can uniquel...

Partial Key : It is a group of attributes that can uniquely identify small entities and that are related to same base entity. It is sometime named as Discriminator.  Altern

What are the disadvantages of relational data, What are the disadvantages o...

What are the disadvantages of relational data ? Disadvantages • Performance - If the number of tables among that relationships to be established are large and the tables t

Describe the definition of a transaction in sql, Describe the definition of...

Describe the definition of a transaction in SQL  Ans: The SQL transaction starts implicitly. Transactions are finished by either Commit work that commits the transaction and st

What is persistency, What is persistency? Persistency ensures which dat...

What is persistency? Persistency ensures which data is stored and that after the object is no longer available (program stops running) the data will be available to other users

Explain projection operation distribute over union operation, Illustrate th...

Illustrate the statement 'Projection operation distributes over the union operation'. Give an example.    Ans: Π L (E 1 ∪ E 2 ) = (Π L (E 1 )) ∪ (Π L (E 2 ))   This says th

Include the create database command, Submit the SQL Statements necessary to...

Submit the SQL Statements necessary to create your database according to the following guidelines: Your SQL statements should exactly mirror your ERD. All primary keys,

Explain the outer join, Define Outer join Outer join - If there are any...

Define Outer join Outer join - If there are any type of values in the one table that do not have corresponding value(s) in the other, in an equi-join which will not be selected

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