PHP Decode

<?php 
 
session_start(); 
 
include '../db.php'; 
 
$first = $_POST['first']; 
$last = $_POST['last']; 
$uid = $_POST['uid']; 
$pwd = $_POST['pwd']; 
 
if (empty($first)) { 
  header("Location: ../signup.php?error=empty"); 
  exit(); 
} 
if (empty($last)) { 
  header("Location: ../signup.php?error=empty"); 
  exit(); 
} 
if (empty($uid)) { 
  header("Location: ../signup.php?error=empty"); 
  exit(); 
} 
if (empty($pwd)) { 
  header("Location: ../signup.php?error=empty"); 
  exit(); 
} else { 
 
  $sql = "SELECT uid FROM user where uid='$uid'"; 
  $result = $conn->query($sql); 
  $uidcheck = mysqli_num_rows($result); 
    if ($uidcheck > 0) { 
      header("Location: ../signup.php?error=username"); 
     exit(); 
    } else { 
 
      $encryptedpassword = password_hash($pwd, PASSWORD_DEFAULT); 
 
 
      $sql = "INSERT INTO user (first, last, uid, pwd) 
      VALUES ('$first', '$last', '$uid', '$encryptedpassword')"; 
      $result = $conn->query($sql); 
 
      header("Location: ../index.php"); 
    } 
 
} 
 
 
 ?>