Solution:Step 1: Understand the subqueryThe subquery selects category IDs where the category name is 'Books'.Step 2: Main query filteringThe main query selects product names where their category_id matches any ID returned by the subquery.Final Answer:Names of products that belong to the 'Books' cate

[Solved] Given the tables:products(id, name, category_id)categories(id, name)What will the following query return?... | PostgreSQL

PostgreSQL - Subqueries in PostgreSQL

Given the tables:
products(id, name, category_id)
categories(id, name)
What will the following query return?

SELECT name FROM products WHERE category_id IN (SELECT id FROM categories WHERE name = 'Books');

AAn error due to incorrect subquery syntax

BNames of all products regardless of category

CNames of categories named 'Books'

DNames of products that belong to the 'Books' category

Step-by-Step Solution

Solution:

Step 1: Understand the subquery
The subquery selects category IDs where the category name is 'Books'.
Step 2: Main query filtering
The main query selects product names where their category_id matches any ID returned by the subquery.
Final Answer:
Names of products that belong to the 'Books' category -> Option D
Quick Check:
Subquery filters categories, main query filters products by those categories [OK]

Quick Trick: Subquery filters IDs; main query filters rows using those IDs [OK]

Common Mistakes:

Confusing product names with category names
Assuming the query returns all products
Thinking the query syntax is incorrect

Master "Subqueries in PostgreSQL" in PostgreSQL

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Visual Try Challenge Project Recall Time

Given the tables:

Step 1: Understand the subquery

Step 2: Main query filtering

Final Answer:

Quick Check:

Want More Practice?