SQL Query Foundations | Dataford Interview Questions

Tell me about your SQL proficiency, including the difference between WHERE and HAVING clauses.

Using the provided tables, demonstrate the distinction by summarizing qualifying completed trades within January 2026. Apply row-level conditions before aggregation and return only users whose qualifying trade volume exceeds 1,000.

Output

One row per qualifying user with user_id, user_name, trade_count, and total_volume
Include only completed January trades and users with total volume greater than 1,000
Order by total_volume descending, then user_name ascending

Schema

users

Column	Type	Description
user_idPK	INT	Unique user identifier
user_name	VARCHAR(100)	Display name of the user

trades

Column	Type	Description
trade_idPK	INT	Unique trade identifier
user_id	INT	User who executed the trade
symbol	VARCHAR(20)	Trading pair
status	VARCHAR(20)	Trade processing status
trade_date	DATE	Trade execution date
volume	DECIMAL(18,2)	Trade volume

Your question is SQL Query Foundations. Start with the requirements and the two tables in the Question tab.

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Problem