php - How to check if MySQL returns null/empty?

Question

In DB I have a table with a field called fk_ownerID. By default, when I add a new table row, the fk_ownerID is empty. In Toad for MySQL, this is shown as {null}. If fk_ownerID is given a value, and I later remove this value, I set fk_ownerID = "".

Now, I have the following code:

$result = $dal->getRowByValue('tableName','id', $_POST['myID']);

// Check to see if any rows where returned
if (mysql_num_rows($result) > 0)
{
  while ($row = mysql_fetch_array($result))
  {
    $ownerID = $row["fk_ownerID"];    
  }
}

Now the variable $ownerID should have a number, or not. But I'm unsure how to check this. Currently I'm doing this:

if ( (strlen($ownerID) == 0) || ($ownerID == '0') || ($ownerID == 'null') )

But I'm pretty sure only one of these tests should be necessary.

What is the best way to check if a row field is empty or null?

Answer 1

Use empty() and/or is_null()

http://www.php.net/empty http://www.php.net/is_null

Empty alone will achieve your current usage, is_null would just make more control possible if you wanted to distinguish between a field that is null and a field that is empty.