在读取Excel工作表时，如果列的值是numberic，那么它在datatable中返回null

我正在从Excel工作表中读取值 . 列通常包含 String ，但有时它可能包含数值 . 将Excel工作表读入数据表数值时，读取为空白 .

它将90004读为 null ，但是如果我按数字对该列进行排序，它会读取数值并将字符串值作为 null ，如果我按字符串对此列进行排序，则它会读取字符串值并将数字设为null .

AC62614 abc     EA  MISC
AC62615 pqr     EA  MISC
AC62616 xyz     EA  MISC
AC62617 test    EA  90004
AC62618 test3   TO  MISC
AC62619 test3   TO  STEEL

我的代码：

public static DataTable ReadExcelFile(FileUpload File1, string strSheetName)
    {
        string strExtensionName = "";
        string strFileName = System.IO.Path.GetFileName(File1.PostedFile.FileName);
        DataTable dtt = new DataTable();
        if (!string.IsNullOrEmpty(strFileName))
        {
            //get the extension name, check if it's a spreadsheet
            strExtensionName = strFileName.Substring(strFileName.IndexOf(".") + 1);
            if (strExtensionName.Equals("xls") || strExtensionName.Equals("xlsx"))
            {
                /*Import data*/
                int FileLength = File1.PostedFile.ContentLength;
                if (File1.PostedFile != null && File1.HasFile)
                {

                    //upload the file to server
                    //string strServerPath = "~/FolderName"; 
                    FileInfo file = new FileInfo(File1.PostedFile.FileName);
                    string strServerFileName = file.Name;
                    string strFullPath =     HttpContext.Current.Server.MapPath("UploadedExcel/" + strServerFileName);
                    File1.PostedFile.SaveAs(strFullPath);

                    //open connection out to read excel
                    string strConnectionString = string.Empty;
                    if (strExtensionName == "xls")
                        strConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="
                                                + strFullPath
                                                + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"";
                    else if (strExtensionName == "xlsx")
                        strConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source="
                                                + strFullPath
                                                + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";

                    if (!string.IsNullOrEmpty(strConnectionString))
                    {
                        OleDbConnection objConnection = new OleDbConnection(strConnectionString);
                        objConnection.Open();
                        DataTable oleDbSchemaTable = objConnection.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
                        bool blExists = false;
                        foreach (DataRow dtr in oleDbSchemaTable.Rows)
                        {
                            //reads from the spreadsheet called 'Sheet1'
                            if (dtr["TABLE_NAME"].ToString() == "" + strSheetName + "$")
                            {
                                blExists = true;
                                break;
                            }
                        }
                        if (blExists)
                        {
                            OleDbCommand objCmd = new OleDbCommand(string.Format("Select * from [{0}$]", strSheetName), objConnection);
                            OleDbDataAdapter objAdapter1 = new OleDbDataAdapter();
                            objAdapter1.SelectCommand = objCmd;
                            DataSet objDataSet = new DataSet();
                            objAdapter1.Fill(objDataSet);
                            objConnection.Close();
                            dtt = objDataSet.Tables[0];
                        }

                    }
                }
            }
        }
        return dtt;
    }