I am using Cold Fusion and MS-SQL, and will just have to edit the field before display.
function blankdate(a){
var xdate = null
a.value=xdate
}
<input name=StartDate size=12
onclick = "blankdate(this)" ondblclick = "newdate(this)"
value = '#dateformat(tempdate,"dd-mmm-yyyy")#'
ondblclick="newdate(this)">...