Top Customers by Transaction Volume | Dataford Interview Questions

Write a SQL query to find the top 10% of customers by transaction volume over the last quarter at HDFC Bank.

Use the customers and transactions tables. Treat transaction volume as the count of posted transactions during the last completed calendar quarter. Exclude customers with no qualifying transactions.

Output

One row per selected customer with customer_id, customer_name, transaction_volume, and customer_rank.
Include the highest-volume 10% of eligible customers, rounding the required count up when necessary.
Order by customer_rank, then customer_id.

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique HDFC Bank customer identifier
customer_name	VARCHAR(100)	Customer's registered name

transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
customer_id	INT	Customer associated with the transaction
transaction_date	DATE	Date on which the transaction was recorded
transaction_status	VARCHAR(20)	Processing status of the transaction

Your question is Top Customers by Transaction Volume. Start with the requirements and the two tables in the Question tab.

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Problem