Problem with n.type IN ... statements

There are a number of sql statements that have code like (or similiar) to

WHERE n.type IN (".str_pad('', count(variable_get('casetracker_project_node_types', array('casetracker_project')))* 5 - 1, "'%s',").")"), variable_get('casetracker_project_node_types',array('casetracker_project')));

which generates a when statement like WHERE n.type IN ('casetracker_project','0','0') with one '0' per type installed on Drupal. Problem is this does not always work. I am running under Windows XP with mySQL 4.1.7 and the resulting query returns no rows. Simplifing the query to WHERE n.type IN ('casetracker_project') works.

This can be achieved by filtering the value of variable_get('casetracker_project_node_types', array('casetracker_project')) using array_filter which removes all the unset (zero) array elements. So using the example statement that would become something like

$project_types = array_filter(variable_get('casetracker_project_node_types', array('casetracker_project')));
WHERE n.type IN (".str_pad('', count($project_types)* 5 - 1, "'%s',").")"),  $project_types);