Uploading Excel sheet in DB

public DataSet GetDataFromExcel(string filePath)
{
    try
    {
    string strConn;
    strConn = "Provider=Microsoft.ACE.OLEDB.12.0;" + "Data Source=" + filePath + ";" + "Extended Properties=\"Excel 12.0 Xml;HDR=YES;IMEX=1;TypeGuessRows=0;ImportMixedTypes=Text\"";
    DataTable dt = new DataTable();
    dt = null;
    using (OleDbConnection oleDB = new OleDbConnection(strConn))
    {
        oleDB.Open();
        dt = oleDB.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
        if (dt == null)
            return null;

        ListItemCollection items = new ListItemCollection();
        int i = 0;

        //if (dt.Rows.Count > 1)
        //return null;  

        for (int rowIndex = 0; rowIndex < dt.Rows.Count; rowIndex++)
        {
            string excelSheetName;
            string lastCharacter = "";

            excelSheetName = dt.Rows[rowIndex]["TABLE_NAME"].ToString();
            excelSheetName = excelSheetName.Replace("'", "");
            lastCharacter = excelSheetName.Substring(excelSheetName.Length - 1, 1);
            if (lastCharacter == "$")
            {
                items.Add(dt.Rows[rowIndex]["TABLE_NAME"].ToString());
            }
        }
        if (items.Count > 1)
            return null;

        string sName;
        string query;

        sName = items[0].ToString();
        sName = sName.Replace("'", "");
        sName = sName.Replace("$", "");

        query = "";
        query = String.Format("select * from [{0}$]", sName);
        OleDbDataAdapter da = new OleDbDataAdapter(query, strConn);
        DataSet ds = new DataSet();
        da.Fill(ds);
        return ds;
    }

    }
    catch (Exception ex)
    {

        throw ex;
    }
}



public static DataSet ImportExceltoDataset(string file)
{
    IExcelDataReader iExcelDataReader = null;

    FileStream oStream = File.Open(file, FileMode.Open, FileAccess.Read);

    iExcelDataReader = ExcelReaderFactory.CreateBinaryReader(oStream);

    iExcelDataReader.IsFirstRowAsColumnNames = true;

    DataSet dsUnUpdated = new DataSet();

    dsUnUpdated = iExcelDataReader.AsDataSet();

    iExcelDataReader.Close();

    return dsUnUpdated;
}