SQL: Transactions Over Threshold | Dataford Interview Questions

Write a SQL query to find all customers who made transactions over a specified amount in the last month.

For deterministic evaluation, use a threshold of 1000 and treat August 2026 as the last month. Include only transactions strictly greater than the threshold. Transactions with a NULL amount are ignored.

Output

One row per qualifying customer.
Columns: customer_id, customer_name, qualifying_transaction_count, and max_transaction_amount.
Include only customers with at least one qualifying transaction, ordered by customer_name ascending, then customer_id ascending.

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique customer identifier
customer_name	VARCHAR(100)	Customer or institutional account name

transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
customer_id	INT	Customer associated with the transaction
transaction_date	DATE	Date the transaction was recorded
amount	NUMERIC(12,2)	Transaction amount

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