SQL Deduping Vendor Imports | Dataford Interview Questions

Write a query to find duplicate records in a vendor import table and keep only the most recent row.

Treat rows with the same vendor_code, invoice_number, and line_number as duplicates. If duplicate rows have the same import timestamp, retain the row with the highest import_id.

Output

Return one retained row per logical vendor invoice line.
Include import_id, vendor_code, invoice_number, line_number, amount, imported_at, and source_file.
Order by vendor_code, invoice_number, line_number, and import_id ascending.

Schema

vendor_imports

Column	Type	Description
import_idPK	INT	Unique identifier for the imported row
vendor_code	VARCHAR(20)	Vendor identifier from the import
invoice_number	VARCHAR(30)	Vendor invoice identifier
line_number	INT	Line number within the invoice
amount	DECIMAL(12,2)	Amount reported for the invoice line
imported_at	TIMESTAMP	Timestamp when the row entered the import table
source_file	VARCHAR(100)	Name of the source file that supplied the row

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