Untitled

index.html
----------

<!DOCTYPE html>
<html>

<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Input</title>
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bulma/0.7.2/css/bulma.min.css">
  <script defer src="https://use.fontawesome.com/releases/v5.3.1/js/all.js"></script>
</head>

<body>
  <section class="section">
    <div class="container">
      <div class="field">
        <label class="label">Input</label>
        <div class="control">
          <input id="query" class="input" type="text" placeholder="Input">
        </div>
      </div>
      <div class="field">
        <a id="submit" class="button">SEND</a>
      </div>
      <div id="result"></div>
    </div>
  </section>

  <script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
  <script>
    $('#submit').click(function() {
      var query = $('#query').val();
      console.log(query);
      $.ajax({
        type: "POST",
        url: "go.php",
        data: {
          query: query
        },
        failure: function(data) {
          console.log(data);
          $('#result').text(data);
        },
        success: function(data) {
          console.log(data);
          var data_back = JSON.parse(data);
          var var = data_back.var;
          $('#result').text(var);
        }
      });
    });
  </script>


</body>

</html>


go.php
------

<?php

error_reporting(E_ALL);
ini_set('display_errors', '1');

$query = htmlspecialchars($_POST['query']);

$configs = include("config.php");

$servername = $configs['sql_server'];
$username = $configs['sql_user'];
$password = $configs['sql_pass'];
$dbname = $configs['sql_db_name'];

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("Something failed: " . $conn->connect_error);
} else {
    $sql = "SELECT * FROM table WHERE var = $query";
    $get_query = $conn->query($sql);
    if ($get_query->num_rows > 0) {
        while ($row = $get_query->fetch_assoc()) {
            $var = $row['var'];
        }
    }

    $data = array('var' => $var);
    echo json_encode($data);
    $conn->close();
}


config.php
----------

<?php
return array(
    'sql_server' => 'localhost',
    'sql_user' => 'XXXX',
    'sql_pass' => 'XXXX',
    'sql_db_name' => 'XXXX'
);