[Solved] What does the EXISTS keyword do in a SQL query? — Ans: Checks if a subquery returns any rows and returns true or false | PostgreSQL

PostgreSQL - Subqueries in PostgreSQL

What does the EXISTS keyword do in a SQL query?

AChecks if a subquery returns any rows and returns true or false

BCounts the total number of rows in a table

CJoins two tables based on a condition

DDeletes rows from a table

Step-by-Step Solution

Solution:

Step 1: Understand the purpose of EXISTS
The EXISTS keyword is used to check if a subquery returns any rows. It returns true if there is at least one row, otherwise false.
Step 2: Compare with other options
Counting rows, joining tables, or deleting rows are different SQL operations unrelated to EXISTS.
Final Answer:
Checks if a subquery returns any rows and returns true or false -> Option A
Quick Check:
EXISTS = true if subquery has rows [OK]

Quick Trick: EXISTS means: 'Is there at least one row?' [OK]

Common Mistakes:

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What does the EXISTS keyword do in a SQL query?