Solution:Step 1: Analyze the subqueryThe subquery selects IDs of categories where active is true.Step 2: Understand the main query filterThe main query selects product names where category_id matches any active category ID.Final Answer:Product names in active categories only. -> Option AQuick Check:

[Solved] Consider the query:SELECT product_name FROM products WHERE category_id IN (SELECT id FROM categories WHERE active = true);What does this query return? | PostgreSQL

PostgreSQL - Subqueries in PostgreSQL

Consider the query:

SELECT product_name FROM products WHERE category_id IN (SELECT id FROM categories WHERE active = true);

What does this query return?

AProduct names in active categories only.

BAll product names regardless of category status.

CProduct names in inactive categories only.

DAn error due to missing JOIN clause.

Step-by-Step Solution

Solution:

Step 1: Analyze the subquery
The subquery selects IDs of categories where active is true.
Step 2: Understand the main query filter
The main query selects product names where category_id matches any active category ID.
Final Answer:
Product names in active categories only. -> Option A
Quick Check:
IN filters products by active categories [OK]

Quick Trick: IN filters main query by subquery results [OK]

Common Mistakes:

Assuming query returns all products
Thinking JOIN is required for this filter
Confusing active and inactive categories

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Consider the query:

Step 1: Analyze the subquery

Step 2: Understand the main query filter

Final Answer:

Quick Check:

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