C# Excel의 데이터를 읽고 혼합 모드로 읽어 데이터 유형 변경을 방지합니다.

        /// <summary>
        /// Read  Excel  to DataSet
        /// </summary>
        /// <param name="filename"></param>
        /// <returns></returns>
        private static DataSet ExcelToDataSet(string filename)
        {
            DataSet ds;
            //HDR=Yes;IMEX=1   HDR Excel  IMEX Excel , 
            string strCon = "Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + filename + ";" + "Extended Properties='Excel 8.0;HDR=Yes;IMEX=1';";
            System.Data.OleDb.OleDbConnection myConn = new System.Data.OleDb.OleDbConnection(strCon);
            string strCom = " SELECT * FROM [Sheet1$]";
            myConn.Open();
            System.Data.OleDb.OleDbDataAdapter myCommand = new System.Data.OleDb.OleDbDataAdapter(strCom, myConn);
            ds = new DataSet();
            myCommand.Fill(ds);
            myConn.Close();
            return ds;
        }