Insert NULL value for Date column in database if the TextBox is Blank in ASP.Net

@MDarwish, you mean like this:

 Here's my code:

Dim com As New SqlCommand("SELECT * FROM tblJOL")
   If txtShipoutDatePlan.Text <> "" Then
      If com.Parameters.Add("DRsda", SqlDbType.VarChar).Value Then
          Dim dateValueSDA As Date
          dateValueSDA = txtShipoutDateActual.Text
          lblDaysda.Text = WeekdayName(Weekday(dateValueSDA))
       End If
   Else
        com.Parameters.Add("DRsda", SqlDbType.VarChar).Value = DBNull.Value
    End If