Question

Match the LIST-I with LIST-II

Choose the correct answer from the options given below:

• A. A-I, B-II, C-III, D-IV
• B. A-II, B-I, C-III, D-IV
• C. A-II, B-I, C-IV, D-III
• D. A-IV, B-II, C-I, D-III

Hint:

Remember:
- Union = All unique rows from both queries.
- Intersect = Only rows common to both.
- Join = Merges tables side-by-side based on column conditions.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks to match various relational algebra and database query operations (List-I) with their primary operational descriptions (List-II).

Step 2: Core Concepts of Relational Operations:
Let us analyze each relational operation:
- A. SELECT: The SELECT statement is the primary command used in SQL to read and retrieve matching data from a database. This matches with description I.
- B. INTERSECT: This set operation takes two relations as input and returns a set containing only the records that are present in both tables (common tuples). This matches with description II.
- C. JOIN: This operation is used to combine columns from two tables based on a common key and specific join conditions. This matches with description III.
- D. UNION: This set operation combines all unique rows retrieved by two compatible queries into a single output list. This matches with description IV.

Step 3: Compiling the Match: Putting the matches together: - A $\rightarrow$ I - B $\rightarrow$ II - C $\rightarrow$ III - D $\rightarrow$ IV - This sequence corresponds directly to option (A).

Step 4: Final Answer:
The correct matching sequence is A-I, B-II, C-III, D-IV.
Hence, option (A) is the correct choice.