ขอวิธีการนำข้อมูลใน excel ที่ต้องตัดบางคอลัมน์เพื่อ importsql หน่อยครับ

try
            {
                string sqlQuery = string.Empty;
                FileInfo workBook = new FileInfo(@"D:\invoice0012.xlsx");
                using (ExcelPackage xlPackage = new ExcelPackage(workBook))
                {
                    ExcelWorksheet invWorksheet = xlPackage.Workbook.Worksheets["Sheet1"];     
                    for (int rowNumber = 10; rowNumber <= 50; rowNumber++)    //ไม่รู้ว่าเริ่มจากแถวไหนและสูงสุดกี่แถว เอาตามที่เห็นก่นอ             
                    {
                         int myVal = 0;
                         object col1Value = invWorksheet.Cells[rowNumber, 1].Value;
                         String myVar = col1Value.ToString();

                         if (int.TryParse(myVar , out myNum)) {         
                             object col2Value = invWorksheet.Cells[rowNumber, 2].Value;
                             object col3Value = invWorksheet.Cells[rowNumber, 3].Value;
                              if(   sqlQuery == string.Empty  ){             
                                   sqlQuery = "insert into (xxxx,xxx) values ( " + col2Value.ToString(); + ","+col3Value.ToString();+")";
                               }else{
                                    sqlQuery += ", ( " + col2Value.ToString(); + ","+col3Value.ToString();+")";    
                               }

                         } else {
                             
                         }
                    }   
                } 
               MessageBox.Show(sqlQuery);
              
            }
            catch (IOException ioEx)
            {
                if (!String.IsNullOrEmpty(ioEx.Message))
                {
                    if (ioEx.Message.Contains("because it is being used by another process."))
                    {                       
                        Console.WriteLine("Could not read example data. Please make sure it not open in Excel.");
                    }
                }
                Console.WriteLine("Could not read example data. " + ioEx.Message);
            }
            catch (Exception ex)
            {
                Console.WriteLine("An error occured while reading example data. " + ex.ToString());
            }