read excel spreadsheet using c# .net

  using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;
using System.IO;
using System.Xml;
using System.Data.OleDb;
 public static void Main(string[] args)
        {
            string fileLocation = System.IO.Path.GetFullPath(@"../../ExcelFiles/Employees.xlsx");
            string connectionString = "";
            string fileExtension = Path.GetExtension(fileLocation);
            if (fileExtension == ".xls")
            {
                connectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"";
            }

            else if (fileExtension == ".xlsx")
            {
                connectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";
            }
            //Create OleDB Connection and OleDb Command
            OleDbConnection con = new OleDbConnection(connectionString);
            OleDbCommand cmd = new OleDbCommand();
            cmd.CommandType = System.Data.CommandType.Text;
            cmd.Connection = con;
            OleDbDataAdapter dAdapter = new OleDbDataAdapter(cmd);
            DataTable dtExcelRecords = new DataTable();
            con.Open();
            DataTable dtExcelSheetName = con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
            string getExcelSheetName = dtExcelSheetName.Rows[0]["Table_Name"].ToString();
            cmd.CommandText = "SELECT * FROM [" + getExcelSheetName + "]";
            dAdapter.SelectCommand = cmd;
            dAdapter.Fill(dtExcelRecords);
            con.Close();

            DateTime startdate = DateTime.Now.Date;
            DateTime enddate = DateTime.Now.Date.AddDays(30);

            foreach (DataRow dr in dtExcelRecords.Rows)
            {
                DateTime DT = DateTime.Parse(dr["Contract expiry date"].ToString());

                if (DT >= startdate && DT <= enddate)
                {
                    Console.WriteLine("Employee Name =>" + dr["Employee name"].ToString() + "Contract Expiry Date =>" + DT.ToShortDateString()); 
 //instead of above line you can write the email sending code here.

                }
            }

            Console.ReadLine();
        }

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