Read and Import Excel data to DataTable using closedXml

protected void Page_Load(object sender, EventArgs e)

{

    DataTable dt = new DataTable();

    dt.Columns.AddRange(new DataColumn[] {

                new DataColumn("Number", typeof(int)),

                new DataColumn("String", typeof(string)),

                new DataColumn("DateTime", typeof(DateTime)),

                new DataColumn("Formula", typeof(string))

            });

    string file = Server.MapPath("~/TestData.xlsx");

    using (XLWorkbook workBook = new XLWorkbook(file))

    {

        IXLWorksheet workSheet = workBook.Worksheet(1);

        bool firstRow = false;

        foreach (IXLRow row in workSheet.Rows())

        {

            if (firstRow)

            {

                foreach (IXLCell cell in row.Cells())

                {

                    dt.Columns.Add(cell.Value.ToString());

                }

                firstRow = false;

            }

            else

            {

                dt.Rows.Add();

                int i = 0;

                foreach (IXLCell cell in row.Cells())

                {

                    if (cell.DataType == ClosedXML.Excel.XLCellValues.Number && !cell.HasFormula)

                    {

                        dt.Rows[dt.Rows.Count - 1][0] = cell.Value.ToString();

                    }

                    else if (cell.DataType == ClosedXML.Excel.XLCellValues.Text && !cell.HasFormula)

                    {

                        dt.Rows[dt.Rows.Count - 1][1] = cell.Value.ToString();

                    }

                    else if (cell.DataType == ClosedXML.Excel.XLCellValues.DateTime && !cell.HasFormula)

                    {

                        dt.Rows[dt.Rows.Count - 1][2] = cell.Value.ToString();

                    }

                    else if (cell.HasFormula && (cell.DataType == ClosedXML.Excel.XLCellValues.Number

                        || cell.DataType == ClosedXML.Excel.XLCellValues.Text || cell.DataType == ClosedXML.Excel.XLCellValues.DateTime))

                    {

                        dt.Rows[dt.Rows.Count - 1][3] = cell.Value.ToString();

                    }

                    i++;

                }

            }

        }

    }

    gvDetails.DataSource = dt;

    gvDetails.DataBind();

}

//Get the ClosedXML sdk from the following link
https://closedxml.codeplex.com/releases/view/197852