You can check the EndDate value in parameter expression, and if it's incorrect, set it to StartDate + 1 Month.
Something like:
= IIF(DateDiff(DateInterval.Month, Parameters!StartDate.Value, Parameters!EndDate.Value) = 0, Parameters!EndDate.Value, AddDate(DateInterval.Month, 1, Parameters!StartDate.Value))
If you just want notify user, you can place some hidden text box with appropriate formatting (red big font) and message about date parameters incorrect range. In Hidden expression set
= (DateDiff(DateInterval.Month, Parameters!StartDate.Value, Parameters!EndDate.Value) <> 0)
Also, you can combine both actions with custom code:
Public DateMessage As String
Public Function ValidateDate(StartDate As DateTime, EndDate As DateTime) As DateTime
Dim ResultDate As DateTime
If (DateDiff(DateInterval.Month, StartDate, EndDate) <> 0) Then
ResultDate = AddDate(DateInterval.Month, 1, StartDate)
DateMessage = String.Format("End Date parameter value {0}
was out of range and was changed to {1}", EndDate, ResultDate)
Else
ResultDate = EndDate
End If
End Function
Then, in Parameter value expression:
= Code.ValidateDate(Parameters!StartDate.Value, Parameters!EndDate.Value)
In Value property of tbDateParameterMessage textbox:
= Code.DateMessage
And in Hidden property expression:
= String.IsNullOrEmpty(Code.DateMessage)
EDIT
But if you want to stop report running, use this custom code:
Public Function CheckDate(SDate as Date, EDate as Date) as Integer
Dim msg as String
msg = ""
If (SDate > EDate) Then
msg="Start Date should not be later than End Date"
End If
If msg <> "" Then
MsgBox(msg, 16, "Parameter Validation Error")
Err.Raise(6,Report) 'Raise an overflow
End If
End Function
It's taken from SQLServerCentral forum.