mysql remove dupe from query e select last insert

qith a query I nedd to join 2 table and from result to remve dupe records but I need to show last insert (is.pr). I try this, but not work :

$query="SELECT is.cf, is.ps, is.pr, is.pn, dati.ma, dati_uni.age, dati_uni.code FROM (SELECT * FROM is ORDER BY is.pr DESC) as temp INNER JOIN dati_uni ON (dati_uni.code=is.ps) GROUP BY is.cf";

thx in advance.