Case Study With SQL | Dataford Interview Questions

Solve a case study + LC + SQL

For the SQL portion, use the provided customer and transaction data. Return every customer with approved transaction activity during 2025, including customers with no qualifying activity.

Output

One row per customer with customer_id, customer_name, approved_transaction_count, total_approved_amount, and activity_level.
Classify customers as High, Standard, or None based on total approved amount: at least 1000, greater than 0, or 0.
Order by total approved amount descending, then customer ID ascending.

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_date	DATE	Date the transaction occurred
amount	NUMERIC(10,2)	Transaction amount
status	VARCHAR(20)	Transaction processing status

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