Question

I form that edits a table in the database. However a user may not selcect an image so if they dont I do not want to update that field. I have tried a couple of ways to do this but none work. Is there an easy way? Thanks.

if ($_POST["image"]!=='') { 
      $image= "image=%s"; 
      $imageValue =    "GetSQLValueString(".$_POST['image'].", 'text'),";
};

$insertSQL = sprintf("UPDATE taxi SET name=%s, taxi_link=%s, ". $image." WHERE id=%s",
                   GetSQLValueString($_POST['name'], "text"),
                   GetSQLValueString($_POST['link'], "text"),
                   $imageValue,
                   GetSQLValueString($_POST['id'], "int"));

Answer 1

If you use a framework like CodeIgniter you can simply:

$arr_values = array('name' => $_POST['name'],
                    'taxi_link' => $_POST['link']);

if ( ! $_POST["image"])
    $arr_values['image'] = $_POST['image'];

$this->db->update($arr_values, array('id' => $_POST['id']));

The update() simply handles an array, and you can simply add additional values to that array based on conditions.

Personally, I made my own function like this one which works perfect with adding and using array values.

Fixed your query:

$image = '';
if ($_POST["image"] !== '')
      $image= ", image=".GetSQLValueString($_POST['image'], 'text');

$insertSQL = sprintf("UPDATE taxi SET name=%s, taxi_link=%s {$image} WHERE id=%s",
                   GetSQLValueString($_POST['name'], "text"),
                   GetSQLValueString($_POST['link'], "text"),
                   GetSQLValueString($_POST['id'], "int"));