从Excel读取数据至DataSet中使用OleDb

 public static DataSet ToDataTable()

    
     {
    
         string connStr = " ";
    
         OpenFileDialog openFile = new OpenFileDialog();
    
         openFile.Filter = "Excel(*.xlsx)|*.xlsx|Excel(*.xls)|*.xls";
    
         openFile.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
    
         openFile.Multiselect = false;
    
         if (openFile.ShowDialog() == DialogResult.Cancel) return null;
    
         var filePath = openFile.FileName;
    
         string fileType = System.IO.Path.GetExtension(filePath);
    
         if (string.IsNu