It's always represent a .NET value. For example if I have a DateTime property with DateTime.Min as value, I will set paremeterMap property attribute nullValue="01/01/0001 00:00:00" to save null in db On a resultMap property the same nullValue="01/01/0001 00:00:00", will transform a database value null to DateTime.Min.
Hopes this help. Just needs to read the doc http://ibatis.apache.org/docs/dotnet/datamapper/ch03s04.html#id357123 You don't need to use a TypeHandler -- Cheers, Gilles <a href="http://www.amazon.com/gp/registry/6JCP7AORB0LE";>Wish List</a>
