Self Intro and SQL Focus | Dataford Interview Questions

Tell me about yourself and walk me through your SQL experience.

For the SQL portion, write a query that demonstrates joining customer and payment data, calculating each customer's successful payment total for 2025, and ranking customers by that total.

Output

One row per customer with at least one qualifying payment.
Columns: customer_id, customer_name, total_paid, and total_rank.
Include only successful payments dated in 2025. Rows with a NULL paid_at are ignored.
Sort by total_paid descending, then customer_id ascending. Tied totals share the same rank.

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique Stripe customer identifier
customer_name	VARCHAR(120)	Customer display name

payments

Column	Type	Description
payment_idPK	INT	Unique payment identifier
customer_id	INT	Customer associated with the payment
amount	NUMERIC(14,2)	Payment amount in the account's settlement currency
status	VARCHAR(60)	Payment processing status
paid_at	TIMESTAMP	Timestamp when the payment was recorded as paid

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Problem