Submission form, set blank forms to NULL

[Mainer82]

I have a HTML form; I want to be able to set it so that if a field is empty, the field in the DB will actually be NULL and not just have the word NULL in the field. I thought that using this code would help, but it just puts the word NULL in the field.

<?php
            if (isset($_POST['oc_item'])) { 
            $oc_item = mysql_escape_string($_POST['oc_item']);
            $oc_itemdesc = (!empty($_POST['oc_itemdesc'])) ? $_POST['oc_itemdesc'] : 'NULL';

           $sql = "INSERT INTO catalog_dev (oc_item,oc_itemdesc)
            VALUES(''$oc_item','$oc_itemdesc')";
        
        mysql_query($SQL);
        if (mysql_query($sql)) {
            echo '<strong><em>Your data has been submitted</em></strong><br /><br />';
                } else {
            echo '<p>Error adding submitted info: ' . mysql_error(). '</p>';
        }
        }
        ?>

<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
        
        <table>
        <tr>
            <td>Item Name</td>
            <td><input class="forms" type="text" size="50" maxlength="50" name="oc_item" /></td>
        </tr>
        <tr>
            <td>Item Description</td>
            <td><input class="forms" type="text" size="50" maxlength="50" name="oc_itemdesc" /></td>
        </tr>
</table>

        <p><input type="submit" value="Submit item" /></p>
        </form>

Any suggestions? Thank you,

[centrex]

The ternary operator is assigning a string value of NULL to $oc_itemdesc if the field is blank. Removing the the quotes around it should yield the expected result.

$oc_itemdesc = (!empty($_POST['oc_itemdesc'])) ? escape($_POST['oc_itemdesc']) : NULL;

[Mainer82]

I tried that, now the field is empty in the database, however it's not actually marked as NULL when being viewed in PHPmyadmin. Is there any way to set it to NULL?