What is the main purpose of using EXISTS in a SQL query?

easy📝 Conceptual Q1 of 15

PostgreSQL - Subqueries in PostgreSQL

What is the main purpose of using EXISTS in a SQL query?

ATo count the number of rows in a table

BTo join two tables based on a condition

CTo check if a subquery returns any rows

DTo update rows in a table

Step-by-Step Solution

Solution:

Step 1: Understand the role of EXISTS
EXISTS checks if the subquery returns at least one row.
Step 2: Compare with other options
Counting rows, joining tables, or updating rows are different SQL operations.
Final Answer:
To check if a subquery returns any rows -> Option C
Quick Check:
EXISTS usage = B [OK]

Quick Trick: EXISTS returns true if subquery has rows, false otherwise [OK]

Common Mistakes:

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