Error on run query : SELECT DISTINCT count(*) as sister_city_count, ref_country.fr_name, ref_country.iso2, fr_article_url FROM sister_city INNER JOIN ref_country ON ref_country.iso2 = sister_city.country GROUP BY sister_city.country,ref_country.iso2,fr_article_url ORDER BY fr_name ; 'choisirsc.ref_country.fr_name' isn't in GROUP BY