In a Database Aplication I need to check if Periodes overlap but I need to diffrentiate between startdates that aren't filled and startdates In an infinate Past

So how do I workaround this problem...
using a nullable(of Date) gives hell as well because a date can contain nothing as well as a minvalue and in some cases it will give a
.hasvalue = False
but in other situtions a .hasvalue = True with a date of Date.Minvalue!


'Just a startdate
Dim StartDate as Date

' code somewhere in the user interface to indicate an infinate startdate
StartDate = Date.Minvalue

' Somewhere in validation of Data before storing in the database
If StratDate is nothing then
'This mesage will appear!!!!!!!
Msgbox("You need to enter a startdate")
end if