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

Draw an er diagram with primary key for a farm, Draw an ER diagram that rep...

Draw an ER diagram that represents the information described below. Show all entity sets, relationship sets, primary keys, and the mapping cardinality of the relationship sets.

ER diagram, sir we want er diagram of bank management system in this main m...

sir we want er diagram of bank management system in this main menu option as new account,deposit amount,withdraw amount,all acount holder list,modify account,close account

What are the reasons for having variable length records, What are the reaso...

What are the reasons for having variable length records? What are the various ways to store variable length records? Variable-length records arise in a database in various wa

Need web-based database, Our company hires independent contractors to insta...

Our company hires independent contractors to install equipment at precise locations across North America. We want to track the installation data and generate reports. The compan

Describe how you can simplify operations, Describe how you can simplify Ope...

Describe how you can simplify Operations. To simplify operation, one should use inheritance, where possible to use, to reduce the quantity of distinct operations. Introduce new

We need help in booking system for golf business, We need help in Booking S...

We need help in Booking System for Golf Business Development of a web based booking system which permits clients to book golf lessons with the following features- a) 4 user p

Advantages of data distribution, Advantages of Data Distribution The pr...

Advantages of Data Distribution The primary benefit of distributed database systems is the ability to access and share data in a reliable and efficient manner.

Advantages of database systems, Problem 1. Describe the following a)...

Problem 1. Describe the following a) Advantages of Database Systems b) Functions of a DBMS Explanation of part (a) and (b) 2. Explain the following concepts w

Datawarehouse, Explain four causes for failures in data warehouse projects

Explain four causes for failures in data warehouse projects

Explain cursors in sql, Explain cursors in SQL? Cursors in SQL - An o...

Explain cursors in SQL? Cursors in SQL - An object used to store the output of a query for row-through-row processing through the application programs. Cursors are constructs

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