Dim dt As Table = Tables("订单")
Dim nms() As String = {"产品","客户","数量","单价","金额","日期"} \'要导出的列名
Dim caps() As String = {"产品名称","用户名称","数量","单价","金额","日期"} \'对应的列标题
Dim szs() As Integer = {100,100,80,80,80,120} \'对应的列宽
Dim Book As New XLS.Book \'定义一个Excel工作簿
Dim Sheet As XLS.Sheet = Book.Sheets(0) \'引用工作簿的第一个工作表
Dim st As XLS.Style = Book.NewStyle \'日期列的显示格式
st.Format = "yyyy-MM-dd"
For c As Integer = 0 To nms.length -1
    Sheet(0, c).Value = caps(c) \'指定列标题
    Sheet.Cols(c).Width = szs(c) \'指定列宽
    If dt.Cols(nms(c)).IsDate Then \'如果是日期列
        Sheet.Cols(c).Style = st \'设置显示格式
    End If
Next
For r As Integer = 0 To dt.Rows.Count - 1 \'填入数据
    For c As Integer = 0 To nms.length -1
        Sheet(r +1, c).Value = dt.rows(r)(nms(c))
    Next
Next
Dim dlg As New SaveFileDialog \'定义一个新的SaveFileDialog
dlg.Filter= "Excel文件|*.xls" \'设置筛选器
If dlg.ShowDialog = DialogResult.Ok Then
    Book.Save(dlg.FileName)
    Dim Proc As New Process
    Proc.File = dlg.FileName
    Proc.Start()
End If

在写入数据时的这新代码中加入判断日期字段的语句,如果为空,则在Excel对应单元写入空值即可.

For r As Integer = 0 To dt.Rows.Count - 1

    For c As Integer = 0 To nms.length -1
     if nms(c)="日期" then

       if dt.rows(r).isnull(nms(c)) then
          Sheet(r +1, c).Value =nothing

       else

          Sheet(r +1, c).Value = dt.rows(r)(nms(c))

      end if

      else

       Sheet(r +1, c).Value = dt.rows(r)(nms(c))
    end if

    Next
Next