Example of relational operations, Database Management System

Assignment Help:

Consider the relation PERSON. If you want to display details of persons having age less than or equal to 30 than the select operation will be used as follows:

σ AGE <=30 (PERSON)

The resultant relation will be as shown:

PERSON_ID

NAME

AGE

ADDRESS

2

Sharad Gupta

30

Pocket 2, Mayur

Vihar.

 

 

 

Note:

1)   Select operation is commutative; i.e.,

σ (R)) = σ (R))

Therefore, series of select can be applied in any order

2) More than one condition can be applied using Boolean operators OR & AND etc.


Related Discussions:- Example of relational operations

Explain the term- signal-to-noise ratio, Explain the term- signal-to-noise ...

Explain the term- signal-to-noise ratio A signal-to-noise ratio of 20 dB means that S/N = 100. As log2101 is around 6.658, the Shannon limit is around 19.975 kbps. The Nyquist

What is trigger, What is Trigger? Trigger: A database trigger is proced...

What is Trigger? Trigger: A database trigger is procedural code which is automatically executed in response to specific events on a particular table in a database. Triggers can

Entity Relationship for music band managem modeliing, i am required to come...

i am required to come up with entities relationships, optionality and cardinality from a scenario. there is a night club and bookings for a musician band

Explain the concept of deadlock, Question: In a multi-user database env...

Question: In a multi-user database environment, locking mechanisms can be used to solve the three basic problems of concurrency. On the other hand, however, locking may also le

Differences among the candidate keys and the primary key, Discuss the diffe...

Discuss the differences among the candidate keys and the primary key of a relation. Give instance to describe your answer? A candidate key is one that can be used as primary ke

Customer service, as a customer service employee, explain five measures you...

as a customer service employee, explain five measures you would recommend a displeased student to patronise a school canteen

Consistency error-database errors, Consistency error : These errors happen ...

Consistency error : These errors happen due to the inconsistent state of database caused may be due to wrong implementation of commands or in case of a transaction abort.  To overc

Compare the two log based recovery schemes, Compare the two log-based recov...

Compare the two log-based recovery schemes in terms of ease of implementation and overhead cost.    Ans:  There are two types of log based recovery techniques: deferred update

Draw the architecture of mysql, Data Base Management System 1. Draw the...

Data Base Management System 1. Draw the Architecture of MySQL and explain about its subsystems briefly. 2. Elaborate with the help of an example the concept of Primary key a

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