title: Is it possible to have a HTML SELECT/OPTION value as NULL using PHP?
body: <p>The following is a snippet from my HTML form which pulls the options from the table rows accordingly.</p>
  
  <p>What I want to do is have the first option value to be NULL so when no choice is made, NULL is entered when the form is submitted to the database.</p>
  
  <pre><code>    &lt;td&gt;Type&lt;/td&gt;
      &lt;td&gt;:&lt;/td&gt;
      &lt;td&gt;&lt;select name="type_id" id="type_id" class="form"&gt;
      &lt;option value=""&gt;&lt;/option&gt;
          &lt;?php 
              $sql = mysql_query("SELECT type_id, type FROM $tbl_add_type") or die(mysql_error());
              while ($row = mysql_fetch_array($sql))
                  {
                      echo "&lt;option value=".$row['type_id']."&gt;" . $row['type'] . "&lt;/option&gt;";
                  }
          ?&gt;
      &lt;/select&gt;*&lt;/td&gt;
  </code></pre>
  
  <p>Is this possible? Or could someone suggest an easier/better way of doing this?</p>
  
  <p>Thanks</p>
  
  <p>Update: Thanks for the answer, I'm using the method detailed below to convert it to NULL.</p>
  
  <pre><code>if ($_POST['location_id'] === '')
                      {
                          $_POST['location_id'] = 'NULL';
                      }
  </code></pre>
  
  <p>However when trying to use this NULL value with the following query it does not work.</p>
  
  <pre><code>UPDATE addresses SET location_id='NULL' WHERE ipid = '4791'
  </code></pre>
  
  <p>I know it needs to be <code>location_id=NULL</code> instead but don't know how to do this...</p>
  
  <p>Update 2: this is how my queries work:</p>
  
  <pre><code>if ($_POST['location_id'] === '')
  {
  $_POST['location_id'] = 'NULL'; // or 'NULL' for SQL
  }
  
  $notes=isset($_POST['notes']) ? mysql_real_escape_string($_POST['notes']) : '';
  //$location_id=isset($_POST['location_id']) ? mysql_real_escape_string($_POST['location_id']) : '';
  $ipid=isset($_POST['ipid']) ? mysql_real_escape_string($_POST['ipid']) : '';
  
  
  $sql="UPDATE addresses 
      SET notes='$notes', location_id='$location_id'
      WHERE ipid = '$ipid'";
  
  
  mysql_query($sql) or die(mysql_error());
  </code></pre>