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

Introduction to database technology, 1. Create the tables for the play-sche...

1. Create the tables for the play-scheme database as specified in the TMA. 2. Enter the data as given in the spreadsheet. 3. Create queries to retrieve specified information

Explain the lock based protocol, Lock Based Protocol A lock is nothing ...

Lock Based Protocol A lock is nothing but a mechanism that tells the DBMS whether a particular data item is being used by any transaction for read/write purpose. As there are t

Explain the advantages of dbms over file oriented system, Explain the main ...

Explain the main advantages of DBMS over File Oriented System ?

Property management database, You are to write a property management databa...

You are to write a property management database program that allows a real estate agent to view, add, search, and save property listings. The program is to do the following: 1.

Update operations, The Update Operations : Update operations are used fo...

The Update Operations : Update operations are used for altering database values. The constraint violations faced by this operation are logically the similar as the problem faced

Differance between join and outer join, Differentiate between join and oute...

Differentiate between join and outer join? Outer joins return all rows from at least one of the tables or views mentioned within the FROM clause, as long as those rows get toge

List the armstrong axioms for functional dependencies, List the Armstrong's...

List the Armstrong's axioms for functional dependencies.  What do you understand by soundness and completeness of these axioms?      Ans: The Armstrong's axioms are: F1:

Dml precompiler in database management system, DML Precompiler All th...

DML Precompiler All the DBMS have two basic sets of Languages - Data Definition Language (DDL) that have the set of commands needed to define the format of the data that is b

Defining internal classes and operations, Defining Internal Classes and Ope...

Defining Internal Classes and Operations When we enlarge algorithms, new classes can be added to the store intermediate results. A complex operation could be looked at, as a c

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