Discussion

In the context of DBMS, consider the two sets T and S given below.

T	S
I: Logical schema	L: Views
II: Physical schema	M: File organization and indexes
III: External schema	N: Relations

Which one of the following is the correct match from T to S ?

Answer: C

The correct match is I - N, II - M, III - L.

The three levels of the ANSI-SPARC architecture:

the logical (conceptual) schema describes the data as relations, their attributes and constraints (N);
the physical schema describes how those relations are stored: file organisation and indexes (M);
the external schema is what each user or application sees, defined as views over the relations (L).

The options that link the logical schema to views or to file organisation, or the physical schema to views, mix up these levels.

No comment is present. Be the first to comment.

Loading…