Please, keep in mind this post was written for Drupal 6 and Views 2! D7/Views 3 sites might not take so kindly to it.
Recently I was looking at creating a new Todo Feature with a due date. I cracked open CCK’s manage fields UI and added a date field, careful to keep in mind that the default value should be no date, which just happens to translate as NULL. You see, for my Todo use case, not all Todos would have a deadline.
My next step was to create a View of all upcoming items. I wanted the next most urgent todo to float to the top of the list. Sadly, NULL counts as 0 in database land, so my carefully clicked Sort was preloading all my urgent todos with all the lowest priority tasks.
Seeing as this was a SQL problem, I googled the ‘net for viable query tweaks. I found a nice article illustrating exactly what I wanted: MySQL Sort Order with NULL. The grand secret? Sort first by whether the duedate is NULL to flip your empty values to the bottom of the result set.
Read on to see how I added this change to my View.