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

What is the used of specifying alias, What is the used of specifying alias?...

What is the used of specifying alias? Specifying alias: is used to rename column or attribute in a table.

Generalization and specialization, design a generalization specialization h...

design a generalization specialization hierarchy for a motor vehicle sales company. the company sells motorcycles, passenger cars, vens and buses.

Express the properties of strings, Express the properties of Strings? ...

Express the properties of Strings? Strings can be case sensitive (or not) which can change the outcome of string operations. You can evaluate whole strings \ just part

Database security, Ask questiwhat is row indicator in database on #Minimum...

Ask questiwhat is row indicator in database on #Minimum 100 words accepted#

Importance of file organisation in database, Importance Of File Organisatio...

Importance Of File Organisation In Database To execute a database efficiently, there are various design tradeoffs needed. One of the most vital ones is the file Organisation. F

Data replication, Data Replication "If a relation R has its copies kept...

Data Replication "If a relation R has its copies kept at two or more sites, then it is considered replicated". But why do we replicate a relation? There are several advan

Define a relation schema, A Relation Schema represented by R(A1, A2, .....

A Relation Schema represented by R(A1, A2, ..., An) is made up of the relation name the list of attributes and R Ai that it contains. A relation is described as a set of tuples

Explain query tree represent relational algebra expression, How does a quer...

How does a query tree represent a relational algebra expression?      Ans: This includes transforming an initial expression (tree) into an equivalent expression (tree) that is

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