Mysql table using LIMIT, breaks randomly - php

Question

When i run the following code it will return 100 users record from a table but when i increase the value of LIMIT from 100 to a greater number like 5000 then it will not return anything.i have total 6000 records in table. So how can i access different number of records like 2000, 3000 or even all 6000 records? kindly Guide what's wrong!
<?php
$db = mysql_connect("localhost","root","");
if (!$db) {
die('Could not connect to db: ' . mysql_error());}
mysql_select_db("distributedsms",$db);
$result = mysql_query("select * from users LIMIT 100", $db);
$json_response = array();
while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
$row_array['user no'] = $row['sno'];
$row_array['mnc'] = $row['mnc'];
$row_array['mcc'] = $row['mcc'];
$row_array['lac'] = $row['lac'];
$row_array['cell id'] = $row['cell id'];
$row_array['lat'] = $row['lat'];
$row_array['lng'] = $row['lng'];
$row_array['address'] = $row['address'];//push the values in the array
array_push($json_response,$row_array);
$users = $json_response;}
$fp = fopen('users_data.json', 'w+');
fwrite($fp, json_encode($json_response));
fclose($fp);
echo json_encode($json_response);
?>

Answer 1

First, enable error reporting in your INI or Script:
<?php error_reporting(E_ALL);
ini_set('display_errors', 1);
This will help you if there is any error/warning in case of low memory allocation or similar.
To fetch all records, you shouldn't use LIMIT, remove LIMIT from your SQL.
i.e. select * from users

Answer 2

You should not use mysql_connect as it is deprecated. Use mysqli_connect instead. Also, I don't think you need to iterate so much, just choose what you want in your select statement.
UPDATE: another factor on why this might be happening can also be the returned information from the database, if you have apostrophes ' in your strings and you try to use json_encode, it will break, you would need to addslashes first.
Try the following, change your LIMIT as you wish, and let me know if you still have those errors:
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "SELECT sno,mnc,mcc,lac,cell_id,lat,lng,address FROM users LIMIT 100";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
$response = array();
while ($row = $result->fetch_assoc()) {
foreach($row as $k => $str){
$row[$k] = addslashes($str);
}
array_push($response, $row);
}
echo json_encode($response);
} else {
echo "0 results";
}
$conn->close();
?>