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

Database backup, Discuss the importance and characteristics of database bac...

Discuss the importance and characteristics of database backup and recovery procedures, then describe the actions that must be detailed in backup and recovery plan

Describe file organisation, Describe file organisation? A file is organ...

Describe file organisation? A file is organized logically as a sequence of records. These records are mapped onto disk blocks. A) Fixed-Length Records Type deposit=record

What is vertical fragmentation, What is vertical fragmentation? Vertica...

What is vertical fragmentation? Vertical fragmentation divides the relation by decomposing the scheme R of relation r.

Explain algorithm of er to relational mapping, Explain algorithm of ER To R...

Explain algorithm of ER To Relational Mapping ? ER-to-Relational Mapping Algorithm: 1) Step 1: Mapping of regular entity types: For each strong entity type E, form a relatio

What are domain constraints, What are domain constraints?  A  domain is...

What are domain constraints?  A  domain is  a  set  of  values  that  might  be  assigned to an attribute  .all  values that appear in a  column of a relation must be taken fro

Define the terms ddl and dml, Define the terms i) DDL ii) DML DDL: Data...

Define the terms i) DDL ii) DML DDL: Data base schema is particular by a set of definitions expressed by a special language known as a data definition language. DML: A data

Division operation, To do the division operation R1 ÷ R2, R2 should be a co...

To do the division operation R1 ÷ R2, R2 should be a correct subset of R1. In the following example R1 have attributes A and B and R2 have only attribute B so R2 is a correct subse

Describe the different raid levels, Describe the different RAID levels.  Di...

Describe the different RAID levels.  Discuss the choices of the different RAID levels for different applications.          Ans:   There are several combinations of these approa

Backward recovery (undo), Backward Recovery (UNDO): In this system the unco...

Backward Recovery (UNDO): In this system the uncommitted changes made by a transaction to a database are undone.  Instead the system is reset to the last consistent state of databa

What is known as fudge factor, What is known as fudge factor? The numbe...

What is known as fudge factor? The number of partitions is enhanced by a small value called the fudge factor, which is usually 20 percent of the number of hash partitions compu

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