Unit 2

Question 1

What is an instance?

Answer 1

Collection of a data in a database at a particular moment

Question 2

Schema

Answer 2

Overall design

Question 3

Subschemas

Answer 3

Having several schemas at view level

Question 4

Vrai ou faux: logical schema is by far the most important, in terms of its effect on application programs, since programmers construct applications by using
the logical schema

Answer 4

Vrai. I was about to say it was the physical one…welp

Question 4

Vrai ou faux: the physical schema can be easily changed without affecting the application program.

Answer 4

Vrai. Since it is hidden beneath the logical schemas

Question 5

ANSI-SPARC can be divided to:

Answer 5

Internal, conceptual and external

Question 6

Internal level

Answer 6

AKA physical level

how data is stored in a storage

File structures and access methods

Data compression and encryption techniques

Question 7

Conceptual

Answer 7

AKA logical(community view)

What is stored and what relationships exist

Abstracts low level complexities of the physical storage

The level app developers work on

Question 8

External

Answer 8

AKA view level

What the end users use