mysql - How to make the code continue the process if the file upload section is empty PHP MYSQLi -

i have problem 1 part of upload section, how make code continue process if upload section empty? make code, everytime skip file button, show echo 'error: ekstensi file tidak di izinkan!'

here code:

insert_form

<form name="pegawai" action="insert-proses.php" method="post" enctype="multipart/form-data">  <table width="700px" align="left" cellpadding="2" cellspacing="0">  <tr>   <td><b>nokom</b></td>   <td><b>:</b></td>   <td><input type="text" name="nokom" size="40" required /></td> </tr> <tr>   <td><b>nip</b></td>   <td><b>:</b></td>   <td><input type="text" name="nip" size="40" required /></td> </tr> <tr>   <td><b>nama</b></td>   <td><b>:</b></td>   <td><input type="text" name="nama" size="40" required /></td> </tr> <tr>   <td><b>foto</b></td>   <td><b>:</b></td>   <td><input name="file" type="file" id="file" /></td> </tr> <tr>   <td></td>   <td></td>   <td><hr/><input type="submit" name="upload" value="upload" /></td> </tr> </table> </form> 

insert-proses

<?php session_start(); include "config.php";  if(isset($_session['superadmin'])) {     if($_post['upload']) {         $nokom      = $_post['nokom'];               $nip        = $_post['nip'];         $nama       = $_post['nama'];           // proses upload file         $allowed_ext  = array('jpg', 'jpeg', 'png', 'gif');         $file_name    = $_files['file']['name']; // nama file         $file_ext     = strtolower(end(explode('.', $file_name))); // merubah nama file         $file_size    = $_files['file']['size']; // size file         $file_tmp     = $_files['file']['tmp_name']; // temp file          // proses pengecekan upload file         if(in_array($file_ext, $allowed_ext) === true) {             if($file_size < 5220350) // max upload file 5 mb / 1mb = 1044070 {                 $lokasi = 'files/'.$nama.'.'.$file_ext;             move_uploaded_file($file_tmp, $lokasi);             $sql = "insert pegawai (nokom,nip,nama,fileext,filegambar)           values('$nokom','$nip','$nama','$file_ext','$lokasi')";              if (mysqli_query($conn, $sql)) {                 echo "<script>alert('insert data berhasil! klik ok untuk melanjutkan');location.replace('pegawai-list.php')</script>";             }              else {                 echo "error updating record: " . mysqli_error($conn);             }         } else             {                 echo '<div class="error">error: besar ukuran file (file size) maksimal 1 mb!</div>';             }     } else         {             echo '<div class="error">error: ekstensi file tidak di izinkan!</div>';         } }  } else       {           echo '<script>alert("anda bukan superadmin! silahkan login menjadi superadminterlebih dahulu");location.replace("index.php")</script>';       } ?> 

any thankful. thanks

jump on complete upload part if there no file uploaded, or better, run upload part in script if file uploaded:

if(isset($_files['file']) && is_array($_files['file'])) {     // code upload , check file }