The built-in filtering in Outlook is powerful, if clunky, but sometimes it doesn't meet your needs. In my case, I wanted to create a filter that showed me incomplete tasks created more than 30 days ago, with no due date. The middle clause was unavaiable in Outlook's filter dialogs, so I had to create one myself using the obscure SQL pane in the filter dialog.

The SQL pane uses SQL DASL syntax to get the value of items stored internally within Outlook using very long CLSIDs. Obscure enough? Basically, this means that this is a way to use a fairly simple syntax to get the values of stuff whose names and values are totally undocumented. Great, huh?

I won't introduce SQL syntax here, I assume you can find it on the Web. I won't introduce the attributes or their values, because I don't know them. I'm sure you can look them up somewhere.

So what's the use of this post? Well, I will show you my filter:

("http://schemas.microsoft.com/mapi/id/{00062003-0000-0000-C000-000000000046}/81050040" IS NULL AND "urn:schemas:calendar:created" <= today(-2629743) AND "http://schemas.microsoft.com/mapi/id/{00062003-0000-0000-C000-000000000046}/811c000b" = 0)

Isn't that awful? The middle statement is the middle statement in my above requirement, so that says "anything created more than that number of seconds, which is about a month, ago".

For limited references, see:

http://blogs.msdn.com/andrewdelin/archive/2005/05/11/416312.aspx

http://blogs.msdn.com/andrewdelin/archive/2005/08/08/448882.aspx