title: Warning: Undefined array key appear in multiple file
body: <p>I'm new to programming and now I'm working on a project, this project already have prototype that is made by senior student, but now there's have multiple error in php file, and I can't find a way to contact him, I google a lot and tried many way to fix it but doesn't work, this is really driving me crazy.</p>
  <p>here some example:</p>
  <pre><code>Warning: Undefined array key &quot;id&quot; in C:\xampp\htdocs\warmhouse\aeadmin.php on line 9
  
   &lt;?php
       $result=All(&quot;select * from admin where id='1&quot;.$_GET[&quot;id&quot;].&quot;'&quot;);
       foreach($result as $row)
       {   
       ?&gt;
  </code></pre>
  <p>and this one:</p>
  <pre><code>C:\xampp\htdocs\warmhouse\aeditu.php on line 5
  &quot; enctype=&quot;multipart/form-data&quot;&gt;
  Warning: Undefined array key &quot;id&quot; in C:\xampp\htdocs\warmhouse\aeditu.php on line 8
  
  &lt;?php 
  
  require_once('sql.php'); ?&gt;
  &lt;h1&gt;ChangeMember&lt;/h1&gt;&lt;br&gt;
  &lt;form id=&quot;form&quot; method=&quot;post&quot; action=&quot;api.php?do=editu&amp;id=&lt;?=$_GET[&quot;id&quot;]?&gt;&quot; enctype=&quot;multipart/form-data&quot;&gt;
  
  &lt;?php
      $result=All(&quot;select *from user where u_id='&quot;.$_GET[&quot;id&quot;].&quot;'&quot;);
        foreach($result as $row)
      {   
      ?&gt;  
  </code></pre>
  <p>basically it's seems like every file that have $_GET or $_POST something like this will have error, if someone need more information, just ask, I've been trying to solve this by myself several weeks, thank you.</p>
  <p>I'm on PC and using xampp and phpmyadmin</p>