This code shows how to delete duplicate rows on pgsql
DELETE
FROM
m_product
WHERE
sku in(
SELECT
sku
FROM
(
SELECT
sku,
count(*)
FROM
m_product
GROUP BY
sku
HAVING count(*) > 1
) a
)
AND em_mg_manufacturer = 1000012
In MYSQL
DELETE
product
FROM
product
WHERE
reference in (
SELECT
reference
FROM
(
select
reference,
count(*)
from
product
GROUP BY reference
having count(*) > 1) a)
AND
product.id_manufacturer = 309