Php script query on mysql - php

Question

So I used php to connect my android app to a mysql database. I tested both the app and the queries on several small databases. Everything worked fine.
Using the old query on a larger database made the php query load forever in the web browser thus not displaying the intended JSON. So I made a new query but it doesn't display any result in the app, plus, it only displays the last result on the query. Is there any way for this to work out correctly?
Old php query that works on small db, but loads forever in the web browser with larger db:
<?php
error_reporting(0);
$response = array();
require_once __DIR__ . '/db_connect.php';
$db = new DB_CONNECT();
$result = mysql_query("SELECT eid,marca,investimento,marcatotal,dataconstituicao,datainicio FROM empresa") or die(mysql_error());
header('content-type: application/json; charset=utf-8');
mysql_query('SET character_set_connection=utf8');
mysql_query('SET character_set_client=utf8');
mysql_query('SET character_set_results=utf8');
if (mysql_num_rows($result) > 0) {
$response["empresa"] = array();
while ($row = mysql_fetch_array($result)) {
$product = array();
$product["eid"] = $row["eid"];
$product["marca"] = $row["marca"];
$product["investimento"] = $row["investimento"];
$product["dataconstituicao"] = $row["dataconstituicao"];
$product["datainicio"] = $row["datainicio"];
array_push($response["empresa"], $product);
}
$response["success"] = 1;
echo json_encode($response);
} else {
$response["success"] = 0;
$response["message"] = "No empresa found";
echo json_encode($response);
}
?>
New php query that I created that displays ONLY the last result in web browser and doesn't show anything in the app on new larger db:
<?php
//error_reporting(E_ALL);
error_reporting(0);
require_once('db_config.php');
$conn = mysql_connect($db_server, $db_user, $db_password) or die(mysql_error());
$db= mysql_select_db($db_database, $conn);
$sql="SELECT eid,marca,investimento,marcatotal,dataconstituicao,datainicio FROM empresa" ;
header('content-type: application/json; charset=utf-8');
mysql_query('SET character_set_connection=utf8');
mysql_query('SET character_set_client=utf8');
mysql_query('SET character_set_results=utf8');
$rs = mysql_query($sql,$conn);
while ($row=mysql_fetch_assoc($rs))
{
$i=0;
foreach($row as $key => $value)
{
if (is_string($key))
{
$fields[mysql_field_name($rs,$i++)] = $value;
}
}
$json_result ["empresa"] = $fields;
}
$response = json_encode($json_result);
print_r($response);
?>

Answer 1

The aswer from Patrick Q is correct:
$json_result ["empresa"] had to be $json_result ["empresa"][] = $fields;
Also, his suggestion helped me solve my problem further since I just removed the success=1 logic alltogether from my app in order for it to work. Thank you all for the help!