[Solved] Given the table orders with columns customer_id and product, what will this query return?SELECT customer_id, ARRAY_AGG(product ORDER BY product) FROM orders GROUP BY customer_id; | PostgreSQL

PostgreSQL - Aggregate Functions and GROUP BY

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

SELECT customer_id, ARRAY_AGG(product ORDER BY product) FROM orders GROUP BY customer_id;

AEach customer_id with an array of their products sorted alphabetically

BEach customer_id with an array of products in random order

CAn error because ORDER BY is not allowed inside ARRAY_AGG

DA single array of all products ignoring customer_id

Step-by-Step Solution

Solution:

Step 1: Understand GROUP BY with ARRAY_AGG
The query groups rows by customer_id and aggregates products per customer.
Step 2: Effect of ORDER BY inside ARRAY_AGG
ORDER BY inside ARRAY_AGG sorts the products alphabetically within each array.
Final Answer:
Each customer_id with an array of their products sorted alphabetically -> Option A
Quick Check:
ARRAY_AGG with ORDER BY sorts values inside arrays [OK]

Quick Trick: Use ORDER BY inside ARRAY_AGG to sort aggregated array elements [OK]

Common Mistakes:

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