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

Load - unload utilities, These permit the user to unload a database or part...

These permit the user to unload a database or parts of a database and reload the data on the similar machine, or on another machine in a dissimilar location. This can be useful in

Each statement should have a where clause, Submit SQL SELECT Statements to ...

Submit SQL SELECT Statements to demonstrate several reports off your database, according to the following guidelines: You must submit at least 5 SELECT Statements. Each

Timestamp type, Do NOT use the timestamp type.  Use separate date and time ...

Do NOT use the timestamp type.  Use separate date and time data types only.  Figure out how to define an SQL insert statement that uses built-in SQL (or MySQL) functions to define

What is storage manager, What is storage manager? A storage manager is ...

What is storage manager? A storage manager is a program module that gives the interface among the low level data keeps in a database and the application programs and queries su

Recovery techniques, Recovery Techniques: After Reading the types of failur...

Recovery Techniques: After Reading the types of failures and database errors, let us talk about how to recover from the failures. Recovery can be complete using/restoring the previ

Explain data models namely relational network - hierarchical, Explain the t...

Explain the three data models namely relational, network and hierarchical and evaluate their relative advantages and disadvantages. Hierarchical Model: In hierarchical model, da

I need label printing program, Project Description: Hi I'm seeking someo...

Project Description: Hi I'm seeking someone to make my dBase application work. I know it's not a 'modern' language but it's what I know. I have written an order program and I ne

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

Fragmentation, let us consider a table having 2200 records and the fixed si...

let us consider a table having 2200 records and the fixed size of the table to be considered as 25.then how many numbers of table is requredto perform horizontal fragmentation

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