What is a view in sql and when can views be updated, Database Management System

Assignment Help:

What is a view in SQL? When can views be updated?

A view is a virtual table which consists of columns from one or more tables. Through it is same to a table; it is stored in the database. It is a query stored as an object. Therefore, a view is an object in that derives its data from one or more tables. These tables are referred to as base or underlying tables.

Views can be updated if they are described on a single table without any aggregate functions could be mapped to an update on the underlying base table under certain conditions.


Related Discussions:- What is a view in sql and when can views be updated

Define data conversion, Define data conversion? Helpful to load data in...

Define data conversion? Helpful to load data into temporary staging tables. Then can write SQL code to do much of data processing. SQL code is simpler and faster to write than

Delete - referential integrity, During the deletion of a tuple two cases ca...

During the deletion of a tuple two cases can happen: Deletion of tuple in relation having the foreign key: In this type of case simply delete the desired tuple. For example, in

Cases of constraint violations, (1)     Insert into PERSON Violated con...

(1)     Insert into PERSON Violated constraint: - Key constraint Reason: - Primary key 1 already exists in PERSON. Dealing: - DBMS could ask the user to provide valid PER

Explain the dynamic hashing techniques, Explain the Dynamic Hashing Techniq...

Explain the Dynamic Hashing Techniques There are two methods in it: extendible hashing - stores an access structure in addition to the file, and therefore is somewhat identica

Explain i command in qbe, Explain I command in QBE ? I : It is the co...

Explain I command in QBE ? I : It is the command in QBE that is used to insert tuple (s) into the database

What create when a primary key combined with a foreign key, What will be cr...

What will be create when a primary key if combined with a foreign key? A primary key if combined with a foreign key it creates Parent-Child relationship between the tables that

What is a relationship called when it is maintained entities, What is a rel...

What is a relationship called when it is maintained between two entities? A relationship is called Binary relationship when it is maintained between two entities.

Implement a cache simulator, You are required to program (in a high level l...

You are required to program (in a high level language such as C, C++, Java) and implement a cache simulator which will have the following inputs and outputs:- INPUTS

Managing database, 10A.53 Code an Oracle Database trigger to enforce the ...

10A.53 Code an Oracle Database trigger to enforce the constraint that an employee can never change his or her department. 10A.54 Code an Oracle Database trigger to allow the

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

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