Top 5 Customers by Month | Dataford Interview Questions

Write a query to find the top 5 customers by transaction volume in a specific month.

For this exercise, transaction volume means the number of transactions. Use June 2025 as the target month and include only transactions whose customer exists in the customers table.

Output

One row per customer, with columns customer_id, customer_name, and transaction_count.
Include only the five customers with the highest transaction count in June 2025.
Sort by transaction count descending, then customer_id ascending to break ties.

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique customer identifier
customer_name	VARCHAR(100)	Customer display name

transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
customer_id	INT	Customer associated with the transaction
transaction_at	TIMESTAMP	Timestamp when the transaction occurred
amount	NUMERIC(12,2)	Transaction amount

Your question is Top 5 Customers by Month. 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