• I also consider that these two SQL scripts are completely different and thus shouldnt be considered alternatives for each other

    SELECT PostCode, COUNT(Postcode)

    FROM

    (

    SELECT DISTINCT Address1, Address2, City, Postcode

    FROM AddressTable

    ) AS Sub

    GROUP BY Postcode

    HAVING COUNT(Postcode) > 1

    and

    SELECT Address1,Address2,City,PostCode,Count(PostCode)

    FROM AddressTable

    GROUP BY Address1,Address2,City,PostCode

    HAVING Count(PostCode) > 1

    This. Can it be corrected in the original article?