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 is a phantom deadlock, What is a Phantom Deadlock? In distributed...

What is a Phantom Deadlock? In distributed deadlock detection, the delay in propagating local information might cause the deadlock detection algorithms to recognize deadlocks

Explain what is relation, Explain What is Relation? A database relatio...

Explain What is Relation? A database relation is a predefined row or column format for storing information in a relational database. Relations are equal to tables.

Describe specialsation and generalization, Describe Specialsation and gener...

Describe Specialsation and generalization? Specialisation /generalization: This is a top down and bottom up approach to the design of database. It displays the IS_A relation

Create a website for online sales of movies, Niles Video Inc. wants to crea...

Niles Video Inc. wants to create a website for online sales of movies (DVD and videotapes). People will be allowed to register as customers on the website and to update their store

What are the constituents of file, What are the Constituents of File? Also ...

What are the Constituents of File? Also elaborates all the possible file operations? A file is organised logically as sequence of record. These records are mapped onto disk blo

Two approaches to store relations in distributed database, What are the two...

What are the two approaches to store relations in distributed database? a) Replication b) Fragmentation

Explain the dynamic hashing techniques, Explain the Dynamic Hashing Techniq...

Explain the Dynamic Hashing Techniques There are two methods in it: extendible hashing - stores an access structure in addition to the file, and therefore is somewhat identica

How does the system cope up with a record crash, How does the system cope u...

How does the system cope up with a record crash when recovery is going on after the first crash? Ans:  In a system the undo and redo operations are needed to be idempotent to c

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