Finding and removing duplicate rows from database

FindRemoveDuplicates.sql

-- SQL databate table dbo.Test with columns Id, FirstName, LastName, TransactionNumber, LastUpdatedDate

-- Select rows that are duplicates without using LastUpdatedDate
-- If needed can insert into a backup/archive table
SELECT t.Id, t.FirstName, t.LastName, t.TransactionNumber, t.LastUpdatedDate
FROM dbo.Test t
LEFT OUTER JOIN (
  SELECT MIN(Id) as Id,
  FirstName, LastName, TransactionNumber
  FROM dbo.Test
  GROUP BY FirstName, LastName, TransactionNumber
) as keepRows
ON t.Id = keepRows.Id
WHERE keepRows.Id IS NULL

-- Delete the duplicate rows
DELETE FROM dbo.Test
FROM dbo.Test t
LEFT OUTER JOIN (
  SELECT MIN(Id) as Id,
  FirstName, LastName, TransactionNumber
  FROM dbo.Test
  GROUP BY FirstName, LastName, TransactionNumber
) as keepRows
ON t.Id = keepRows.Id
WHERE keepRows.Id IS NULL