SQL Deduplication Strategy | Dataford Interview Questions

Write SQL to find duplicate records and remove them while keeping the latest row per key.

Use the records table. Treat source_system and record_key together as the logical key. The latest row has the greatest updated_at; break timestamp ties by the greatest id.

Output

Return the deleted rows with columns id, source_system, record_key, updated_at, and payload.
Sort deleted rows by id ascending.

Schema

records

Column	Type	Description
idPK	INT	Unique row identifier
source_system	VARCHAR(50)	System that supplied the record
record_key	VARCHAR(100)	External logical key used for deduplication
updated_at	TIMESTAMP	Timestamp of the latest source update
payload	TEXT	Record content

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