SQL Duplicate Rows Query | Dataford Interview Questions

Write a query to return all duplicate rows in a table based on three columns.

Use the provided trade_records table. Treat rows with the same values across client_code, instrument_symbol, and venue_code as duplicates. Rows with NULL values in these columns should be evaluated consistently as part of the same combination.

Output

Return record_id, client_code, instrument_symbol, and venue_code.
Include every row belonging to a repeated three-column combination, not just one representative row.
Sort the result by record_id in ascending order.

Schema

trade_records

Column	Type	Description
record_idPK	INT	Unique identifier for the record
client_code	VARCHAR(20)	Client reference used in the duplicate key
instrument_symbol	VARCHAR(20)	Instrument symbol used in the duplicate key
venue_code	VARCHAR(20)	Execution venue used in the duplicate key

Your question is SQL Duplicate Rows Query. Start with the requirements and the one table in the Question tab.

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Problem

Write a query to return all duplicate rows in a table based on three columns.

Output

Return record_id, client_code, instrument_symbol, and venue_code.
Include every row belonging to a repeated three-column combination, not just one representative row.
Sort the result by record_id in ascending order.

Schema

trade_records

Column	Type	Description
record_idPK	INT	Unique identifier for the record
client_code	VARCHAR(20)	Client reference used in the duplicate key
instrument_symbol	VARCHAR(20)	Instrument symbol used in the duplicate key
venue_code	VARCHAR(20)	Execution venue used in the duplicate key

Your question is SQL Duplicate Rows Query. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.