Writing Business-Flavored SQL | Dataford Interview Questions

Can you provide an example of a business-flavored SQL query you have written for American Express operations or transaction processing?

Using the supplied American Express merchant and transaction tables, return qualifying merchant activity for January 2025. Include merchants with at least two transactions during the period and calculate their approval metrics.

Output

One row per qualifying merchant with merchant_id, merchant_name, transaction_count, approved_transaction_count, approved_amount, and approval_rate
Exclude merchants with fewer than two January transactions
Order by approved_amount descending, then merchant_id ascending

Schema

merchants

Column	Type	Description
merchant_idPK	INT	Unique merchant identifier
merchant_name	VARCHAR(100)	Merchant display name
merchant_category	VARCHAR(50)	Merchant category

transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
merchant_id	INT	Merchant associated with the transaction
transaction_date	DATE	Date the transaction was processed
amount	DECIMAL(12,2)	Transaction amount in US dollars
status	VARCHAR(20)	Transaction processing status

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Problem