[Solved] Given the table orders with columns customer_id, product_id, and quantity, what will this query return?SELECT customer_id, product_id, SUM(quantity) FROM orders GROUP BY customer_id, product_id; | SQL

SQL - GROUP BY and HAVING

Given the table orders with columns customer_id, product_id, and quantity, what will this query return?

SELECT customer_id, product_id, SUM(quantity) FROM orders GROUP BY customer_id, product_id;

ATotal quantity ordered for all orders

BTotal quantity ordered per customer only

CTotal quantity ordered per product only

DTotal quantity ordered per customer and product combination

Step-by-Step Solution

Solution:

Step 1: Understand GROUP BY columns
The query groups rows by both customer_id and product_id, so each group is a unique pair.
Step 2: Analyze aggregation
SUM(quantity) calculates total quantity for each customer-product pair.
Final Answer:
Total quantity ordered per customer and product combination -> Option D
Quick Check:
GROUP BY multiple columns aggregates per unique column pairs [OK]

Quick Trick: SUM with GROUP BY multiple columns sums per unique pairs [OK]

Common Mistakes:

MISTAKES

Assuming aggregation is per single column
Ignoring grouping columns in result
Confusing SUM with COUNT

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More SQL Quizzes

Given the table orders with columns customer_id, product_id, and quantity, what will this query return?

Step 1: Understand GROUP BY columns

Step 2: Analyze aggregation

Final Answer:

Quick Check:

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