SQL for Purchase Within 24 Hours | Dataford Interview Questions

Identify users who made a purchase within 24 hours of receiving a promotional text, ensuring you account for duplicate messages.

Use the provided Attentive-style user, promotional message, and purchase data. Treat the 24-hour boundary as inclusive and include only purchases after or at the message timestamp.

Output

Return one row per qualifying user with user_id, user_name, and first_qualifying_purchase_at.
Exclude users without a qualifying purchase and sort by user_id ascending.

Schema

users

Column	Type	Description
user_idPK	INT	Unique user identifier
user_name	VARCHAR(100)	User display name
email	VARCHAR(255)	User email address

promotional_messages

Column	Type	Description
message_idPK	INT	Unique message record identifier
user_id	INT	Recipient user identifier
campaign_code	VARCHAR(50)	Promotional campaign identifier
sent_at	TIMESTAMP	Timestamp when the text was sent
message_type	VARCHAR(30)	Message classification

purchases

Column	Type	Description
purchase_idPK	INT	Unique purchase identifier
user_id	INT	Purchasing user identifier
purchased_at	TIMESTAMP	Timestamp when the purchase occurred
amount	DECIMAL(10,2)	Purchase amount

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