<?php
$host = 'localhost';
$username = 'dbuser';
$password = 'dbpass';
$db_name = 'dbname';
$table_name = 'tablename';

$db_conn = mysqli_connect($host, $username, $password) or die('Error: Could not connect.');
mysqli_select_db($db_conn, $db_name) or die('Error: Could not select database.');
$result = mysqli_query($db_conn, "SELECT * from " . $table_name) or die('Error: Could not query.');

$json = array();
if (mysqli_num_rows($result)) {
  while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) {
    $json['rawData'][] = $row;
  }
}

// for debug
//echo json_encode($json, JSON_NUMERIC_CHECK | JSON_PRETTY_PRINT);

// for production
echo json_encode($json, JSON_NUMERIC_CHECK | JSON_PRETTY_PRINT);

mysqli_close($db_conn);
?>