sql_query: select sub.autore, sub.id from (SELECT jmb_joodb_sample2.autore,jmb_joodb_sample2.id FROM jmb_joodb_sample2 where Pubblicato=1 ORDER BY RAND()) as sub inner join jmb_joodb_autoriinevidenza on jmb_joodb_autoriinevidenza.autore=sub.autore WHERE sub.autore is not null group by sub.autoresql_query: select sub.autore, sub.id from (SELECT jmb_joodb_sample2.autore,jmb_joodb_sample2.id FROM jmb_joodb_sample2 where Pubblicato=1 ORDER BY RAND()) as sub inner join jmb_joodb_autoriinevidenza on jmb_joodb_autoriinevidenza.autore=sub.autore WHERE sub.autore is not null group by sub.autore