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

Define instance and schema, Define instance and schema?  Instance:  C...

Define instance and schema?  Instance:  Collection of  data  kept in the  data  base  at  a  particular  moment  is  known as an Instance of the database.  Schema: The o

Data dictionary, The database is to record information about artists for a ...

The database is to record information about artists for a (music) production company. An artist is the name of a singer or band; the name of the artist, the year the artist started

Design and building a distributed information system, prototype of a distri...

prototype of a distributed information system for a national car part retail outlet chain.

What is data block, What is data block? Data Block - In oracle the data...

What is data block? Data Block - In oracle the data blocks are referred to as tablespaces. A tablespace is an fields of disk consisting of one or more disk files. A tablespace

Explain an attributes, What are attributes? Give examples. An entity is...

What are attributes? Give examples. An entity is shown by a set of attributes. Attributes are descriptive properties possessed by every member of an entity set. Example: pos

What is relational dbms, What is Relational DBMS This is our subject of...

What is Relational DBMS This is our subject of study. A DBMS is relational if the data is organized into relations, that is, tables. In RDBMS, all data are kept in the well-kno

Data base model, why are older data base model are being replaced by new da...

why are older data base model are being replaced by new data model

Example for while until, Assume you are given a uniprocessor system with on...

Assume you are given a uniprocessor system with one gigabyte of memory and a 300 gigabyte disk. The OS on the machine has a demand paged virtual memory system with a local page rep

Describe deductive databases and relational databases, Problem : (b) A ...

Problem : (b) A deductive database system is essentially the outcome of applying mathematics logic to database management, where logic is used for both data representation and

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