How to get data from a database using a loop? - arrays

Question

In my database I've got different username: "fabio97", "antonino", "lauretta". I want to get them from DB to have an array like this:
$dati = array("str"=>array("n1"=>"fabio97", "n2"=>"antonino", "n3"=>"lauretta"));
is it correct write:
...
"str" => array("n".$i=>"Ti sei incrociato con ".$array_db[username]),
...
into a loop
...
$i = 0;
$array_user = mysql_fetch_array($query);
while ($array_db = mysql_fetch_array ($query_db)) {
...
if ($array_user[square] == $array_db[square]) {
$dati = array(
"data" => array(
'address_complete'=>$data->results[0]->formatted_address,
'address_square'=>$data->results[0]->address_components[1]->long_name,
'location'=>$data->results[0]->address_components[2]->long_name,
'postal_code'=>$data->results[0]->address_components[7]->long_name,
'data_ora'=>$tmp_date
),
"str" => array("n".$i=>"Ti sei incrociato con ".$array_db[username]),
"index" => $i
);
$i++;
}
}
and to call them with Ajax:
... success:function(msg){
if(msg){
$("#location").html(Object.keys(msg.str).map(x => msg.str[x]).join(", "));
}else{
$("#location").html('Not Available');
}