Added GetAllUsernameAndPassword method

src/model/User.php

@@ -37,6 +37,19 @@ class User {
         }
     }
 
+    public static function GetAllUsernameAndPassword(PDO $conn) {
+        try {
+            $users = $conn->query("SELECT username, password FROM user")->fetchAll();
+            foreach ($users as $record) {
+                $result[$record['username']] = $record['password'];
+            }
+            return $result;
+        } catch (PDOException $e) {
+            echo "Error: ".$e->getMessage();
+            return false;
+        }
+    }
+
     public static function GetUserById($id, PDO $conn) {
         try {
             $stmt = $conn->prepare("SELECT * FROM user WHERE id=?");