这样也行
Dim Book1 As New XLS.Book(ProjectPath & "Attachments\订单.xls")
Dim Sheet As XLS.Sheet = Book1.Sheets(0)
Dim St2 As XLS.Style = Book1.NewStyle() '这段格式化日期的代码怎么不起作用???
St2.BorderTop = XLS.LineStyleEnum.Thin
St2.BorderBottom = XLS.LineStyleEnum.Thin
St2.BorderLeft = XLS.LineStyleEnum.Thin
St2.BorderRight = XLS.LineStyleEnum.Thin
St2.Format = "yyyy-MM-dd"
Sheet(3,tables("订单").cols.Count).Style = St2
Book1.Build() '生成细节区
Book1.Save(ProjectPath & "reports\订单.xls")
Dim Proc As New Process '打开工作簿
Proc.File = ProjectPath & "reports\订单.xls"
Proc.Start()