256 views
0 votes
0 votes
External schema consists of:

a) Subschemas

b) Virtual Tables

c) Both a and b

d) None of these

1 Answer

0 votes
0 votes

According to me d answer should be b) Virtual Tables which in turn r nothing but views. :) 

In database theory, a view is the result set of a stored query on the data, which the database users can query just as they would in a persistent database collection object. This pre-established query command is kept in the database dictionary. Unlike ordinary base tables in a relational database, a view does not form part of the physical schema: as a result set, it is a virtual table computed or collated dynamically from data in the database when access to that view is requested.

Related questions

0 votes
0 votes
1 answer
2
Abhijeet_Kumar asked Dec 8, 2017
284 views
0 votes
0 votes
1 answer
4
sh!va asked Nov 7, 2016
2,017 views
What is the difference between database model and database schema? Any useful link please....