Add php files to communicate with the database

All previous routes of the nodejs server are now working with php.

server/database.php

@@ -0,0 +1,43 @@
+<?php
+
+// Singleton to connect db.
+class database
+{
+    // Hold the class instance.
+    private static $instance = null;
+    private $conn;
+
+    private $host = 'localhost';
+    private $user = 'root';
+    private $pass = '';
+    private $name = 'fe_charts';
+    private $port = '';
+
+    // The db connection is established in the private constructor.
+    private function __construct()
+    {
+        try {
+            $this->conn = new PDO(
+                "mysql:host={$this->host};dbname={$this->name};port={$this->port}",
+                $this->user,
+                $this->pass
+            );
+        } catch (PDOException $e) {
+            die('Connection failed: ' . $e->getMessage());
+        }
+    }
+
+    public static function getInstance()
+    {
+        if (!self::$instance) {
+            self::$instance = new database();
+        }
+
+        return self::$instance;
+    }
+
+    public function getConnection()
+    {
+        return $this-> conn;
+    }
+}