Inner Join vs Outer Join | Dataford Interview Questions

Explain the difference between inner join and outer join in SQL.

Use the provided users and orders tables to demonstrate the difference with matching and unmatched records. Show the results from both join types in one result set.

Output

Columns: join_type, user_id, user_name, order_id, amount
Include matching rows for both join types and unmatched rows for the outer join
Sort by join type, then user ID and order ID

Output details

Use INNER JOIN and FULL OUTER JOIN as the exact join_type values.
Sort join_type descending, then user_id ascending with NULLs last, then order_id ascending with NULLs last.
Preserve duplicate rows between the two join results rather than deduplicating them.

Schema

users

Column	Type	Description
user_idPK	INT	Unique user identifier
user_name	VARCHAR(100)	User's display name

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
customer_id	INT	User who placed the order
amount	NUMERIC(10,2)	Order amount

Your question is Inner Join vs Outer Join. Start with the requirements and the two tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem