<p>I want to have CListCtrl.EditLabel() for any column of the list. How can I implement such a feature?</p>

Description is a reserved word - put some [] brackets around it in the SELECT statement
EDIT
Try naming the column something besides Description
Also are you sure you are using the same values in the where clause - because it is a left join so the Description field will be blank if there is no corresponding record in dbo_part
EDIT AGAIN
If you are getting funny results - try a Compact/Repair Database - It might be corrupted