[Solved] What is the primary advantage of using a scalar subquery within the SELECT clause in SQL? — Ans: To compute a single value based on related data for each row | SQL

SQL - Subqueries

What is the primary advantage of using a scalar subquery within the SELECT clause in SQL?

ATo filter rows before aggregation

BTo return multiple rows for each row in the main query

CTo join two tables without specifying a join condition

DTo compute a single value based on related data for each row

Step-by-Step Solution

Solution:

Step 1: Understand scalar subquery
A scalar subquery returns exactly one value for each row in the outer query.
Step 2: Purpose in SELECT clause
It allows calculation or retrieval of a single related value per row, such as a count or a name.
Final Answer:
To compute a single value based on related data for each row -> Option D
Quick Check:
Scalar subqueries return one value per row [OK]

Quick Trick: Scalar subquery returns one value per row [OK]

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What is the primary advantage of using a scalar subquery within the SELECT clause in SQL?