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

Sql query for testing triggers and stored procedures , Demonstrate your kno...

Demonstrate your knowledge of PL/SQL programming by writing and thoroughly testing triggers and stored procedures associated with an e-commerce application that provides security l

Explain instance and schemas, Explain Instance and schemas? Instances ...

Explain Instance and schemas? Instances and schemas: Databases changes over time as the information is deleted and inserted. The collection of information stored in database

Objectives of data management, The traffic data mgmt. systems infrastructur...

The traffic data mgmt. systems infrastructure plan describes the software, hardware, data network, and other elements that will support the TDMS. The infrastructure plan is based o

What are the advantages of embedded query language, What are the advantages...

What are the advantages of embedded query language? Give an example of an embedded SQL query. Embedded query language - SQL could be implemented within two ways. It can be us

Ans the following, discuss the array implementation of a stack.

discuss the array implementation of a stack.

Relationship cardinality, Cardinality shows the number of instances of an e...

Cardinality shows the number of instances of an entity associated with another entity participating in a relationship. Depend on the cardinality binary relationship can be further

Create the database in oracle using ddl, The Assessment page has a link to ...

The Assessment page has a link to download a conceptual model, and a list of data. You are to map this conceptual model, and create the database in Oracle using your own DDL.  T

Explain domain-oriented relational calculus?, How does Tuple-oriented relat...

How does Tuple-oriented relational calculus vary from domain-oriented relational calculus? The tuple-oriented calculus uses a tuple variables i.e., variable whose only allowed

Illustrate the definition of the classes and operation, The definition of t...

The definition of the classes and operation can often be adjusted to increase the amount of inheritance". Justify the above statement.   Adjustment of Inheritance The def

Describe the primary key functions, Describe the primary key functions? ...

Describe the primary key functions? Primary Key : The primary key is an attribute or a set of attributes in which uniquely identify a specific example of an entity. Every entit

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