How to delete duplicate records from SQL Server table

This can be done in 4 simple steps, utilizing temp tables.

First you need to identify duplicate records and insert them into a temp table:

INSERT INTO #mytemptbl
SELECT * FROM Table1
GROUP BY field1, field2, field3
Having COUNT(*) > 1

Then delete those records from the original table:

DELETE FROM Table1
FROM Table1
INNER JOIN #mytemptbl
ON  Table1.field1 = #mytemptbl.field1
AND Table1.field2 = #mytemptbl.field2
AND Table1.field3 = #mytemptbl.field3

Next re-insert records from temp table into the original table:

INSERT INTO Table1
SELECT * FROM #mytemptbl

And finally drop temp table:

DROP TABLE #mytemptbl