I tried this way to see the results of a query and it works!!
$Conn = odbc_connect
("bbdd_usuaris","","",SQL_CUR_USE_ODBC );
$result=odbc_exec($Conn,"select nom from usuaris;");
while(odbc_fetch_row($result)){
for($i=1;$i<=odbc_num_fields($result);$i++){
echo "Result is ".odbc_result($result,$i);
}
}