Question

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 ?

• A. I - L, II - M, III - N
• B. I - M, II - L, III - N
• C. I - N, II - M, III - L
• D. I - N, II - L, III - M

Hint:

External schema equals Views, Logical schema equals Relations, and Physical schema equals File organization and indexes.

Answer 1

The Correct Option is C

Step 1: Think of the three schema levels from top to bottom, starting from what a user or application actually sees down to how data physically sits on disk. At the very top, a user interacts with a customized view of the data - this is the external schema, which corresponds to Views (L).
Step 2: Just below the external level sits the logical schema, which defines the complete set of relations and their attributes existing in the database as a whole, independent of any single user's view. This corresponds to Relations (N).
Step 3: At the lowest level is the physical schema, concerned purely with implementation: how records are laid out in files and which indexes are built to speed up access. This corresponds to File organization and indexes (M).
Step 4: Reading off I to III in this top-down order: Logical schema pairs with N, Physical schema pairs with M, and External schema pairs with L, giving I - N, II - M, III - L.
Final Answer: Option (C)