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

Explain the togaf framework for enterprise architectures, Question: (a)...

Question: (a) With the help of a diagram, explain the TOGAF framework for enterprise architectures. (b) Where would you position enterprise architectures in an enterpri

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

Decomposition, properties of derirable decomposition

properties of derirable decomposition

What is called as recursive partitioning, What is called as recursive parti...

What is called as recursive partitioning? The system repeats the splitting of the input unless each partition of the build input fits in the memory. Such partitioning is known

Ddl compiler-database management system, DDL Compiler The DDL compile...

DDL Compiler The DDL compiler changes the data definition statements (such as CREATE TABLE .... in SQL) into a set of tables having metadata tables. These tables have infor

Modular growth, Modular growth: In distributed environments, it is simple t...

Modular growth: In distributed environments, it is simple to expand. Latest sites can be added to the network without affecting the operations of other sites, as they are somewhat

Differance between internal and external schema, Differance between interna...

Differance between internal and external schema? Internal and external schema: Internal Schema • Describes the physical storage structure • Uses a physical data model External

Explain naivebayessimple algorithem, Use the IRIS dataset that comes with W...

Use the IRIS dataset that comes with Weka to compare the classification performance of the following algorithms. 1. NaiveBayesSimple 2. MultiLayerPerceptron J48 (

Determine the operation that do not participate to be union, 1. Which relat...

1. Which relational algebra operations do not need the participating tables to be union-compatible? Ans: Join is the relational algebra operations that do not need the particip

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