Alter table command, Database Management System

Assignment Help:

ALTER TABLE Command: This command is used for variation of existing structure of the table in the given situation:

  • When a new column is to be added to the table structure.
  • When the existing column definition has to be altered, i.e., changing the width of the data type or the data type itself.
  • When integrity constraints have to be dropped or included.
  • When a constraint has to be allowed or not allowed.

Syntax

ALTER TABLE

ADD ( ...); ALTER TABLE
MODIFY ( ...);

ALTER TABLE

ADD CONSTRAINT < constraint type>(field name);

ALTER TABLE

DROP;

ALTER TABLE

ENABLE/DISABLE ;

You require to put many constraints like that the database integrity is not compromised.

 


Related Discussions:- Alter table command

A distributed transaction, A Distributed Transaction Let us demonstrate...

A Distributed Transaction Let us demonstrate the concept of a distributed transaction by considering a banking system having of three branches located in 3 different cities. Ev

Physical model of traffic data management, After the completion of the logi...

After the completion of the logical model the physical model is to be made. The oracle 10 G will be used as a database server and all the tables with their column are created and i

Explain the function of input controls, Explain the function of input contr...

Explain the function of input controls. Identify four types of input control and explain the function of each. Provide an example of a data integrity error that could occur i

Hass, waht is a repeating group?

waht is a repeating group?

What is difference among mysql_connect and mysql_pconnect, What is differen...

What is difference among mysql_connect and mysql_pconnect? Mysql_connect() opens a new connection to the database while mysql_pconnect() opens persistent connection to the data

Define the concept of generalization, Define the concept of generalization ...

Define the concept of generalization A generalization is relationship between specific kind of thing and general thing. It is also known as "is-a-kind-of" relationship. Inher

Cost of reading a file , A file of employee have 10,000 blocks on a cylinde...

A file of employee have 10,000 blocks on a cylinder of a disk with characteristics r=8ms and btt=0.6ms I want to know the cost of read inthe file under following conditions for a q

Explain er model, Question 1 Explain ER model Question 2 What are the...

Question 1 Explain ER model Question 2 What are the characteristics of a computer provided information? Question 3 What are facts and guidelines to be considered when se

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