Compare excel sheet data with database table data in ASP.Net

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private DataTable GetSqlTable()
        {
            DataTable dt = new DataTable();
            DataColumn idColumn = new DataColumn("id", typeof(string));
            DataColumn nameColumn = new DataColumn("name", typeof(string));
            DataColumn addressColumn = new DataColumn("address", typeof(string));
            dt.Columns.Add(idColumn);
            dt.Columns.Add(nameColumn);
            dt.Columns.Add(addressColumn);

            DataRow row = dt.NewRow();
            row[idColumn.ColumnName] = "1";
            row[nameColumn.ColumnName] = "c";
            row[addressColumn.ColumnName] = "c1";
            dt.Rows.Add(row);

            row = dt.NewRow();
            row[idColumn.ColumnName] = "5";
            row[nameColumn.ColumnName] = "h";
            row[addressColumn.ColumnName] = "h1";
            dt.Rows.Add(row);

            return dt;  //for testing, Instead connecting to database, I created the datatable in code-behind dynamically.

        }

        private DataTable ReadExcelTable()
        {
            string filePath = Server.MapPath("upload/test.xls");
            string connectionString = string.Format(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=""Excel 8.0;HDR=YES;""", filePath);
            DataTable dt = null;
            DbProviderFactory factory =
              DbProviderFactories.GetFactory("System.Data.OleDb");

            using (DbConnection connection = factory.CreateConnection())
            {
                connection.ConnectionString = connectionString;

                using (DbCommand command = connection.CreateCommand())
                {
                    // Cities$ comes from the name of the worksheet
                    command.CommandText = "SELECT * FROM [Sheet1$]";

                    connection.Open();
                    using (DbDataAdapter adapter = factory.CreateDataAdapter())
                    {
                        adapter.SelectCommand = command;
                        DataSet ds = new DataSet();
                        adapter.Fill(ds);
                        dt = ds.Tables[0];

                    }
                }
            }
            return dt;
        }

       private void CheckInsertAndUpdateColumnOfExcel()
        {
            DataTable excelTable = ReadExcelTable();
            DataTable sqlTable = GetSqlTable();

            DataRow[] excelRowsList = excelTable.Select();
            DataRow[] sqlTableList = sqlTable.Select();

            string[] oldSqlIdList = new string[sqlTableList.Count()];
            int index = 0;
            foreach (DataRow row in sqlTableList)
            {
                oldSqlIdList[index] = row[0].ToString();
                index++;
            }

            var list = from x in excelRowsList
                       join s in sqlTableList on x[0].ToString() equals s[0].ToString()
                       select x;

            var list2 = from x in excelRowsList
                        where !oldSqlIdList.Contains(x[0].ToString())
                        select x;

            DataRow[] updateColumn = list.ToArray();  //get the update column
            DataRow[] insertColumn = list2.ToArray();  //get the insert column

            List<string> updateIdList = new List<string>();
            List<string> insertIdList = new List<string>();
            foreach (DataRow row in updateColumn)
            {
                updateIdList.Add(row[0].ToString());
            }
            foreach (DataRow row in insertColumn)
            {
                insertIdList.Add(row[0].ToString());
            }


            Response.Write("the rows id need to update are " + string.Join(",", updateIdList.ToArray()));
            Response.Write("<br/>");
            Response.Write("the rows id need to insert are " + string.Join(",", insertIdList.ToArray()));

        }

protected void Button1_Click(object sender, EventArgs e)
        {

            CheckInsertAndUpdateColumnOfExcel();
        }