здесь код для экспорта данных в Excel
StringWriter sw = new StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
string attachment = "attachment; filename=excel" + ".xls";
Response.ClearContent();
Response.AddHeader("content-disposition", attachment);
rptMain.DataBind();
rptMain.RenderControl(htw);
Response.Write(sw.ToString());
Response.Flush();
Response.End();
и вот код для импорта данных из Excel
DbProviderFactory factory = DbProviderFactories.GetFactory("System.Data.OleDb");
DbDataAdapter adapter = factory.CreateDataAdapter();
DbCommand selectCommand = factory.CreateCommand();
selectCommand.CommandText = "SELECT ColumnNames FROM [Sheet1$]";
DbConnection connection = factory.CreateConnection();
connection.ConnectionString = connectionString;
selectCommand.Connection = connection;
adapter.SelectCommand = selectCommand;
DataTable dtbl = new DataTable();
adapter.Fill(dtbl);
if (dtbl.Rows.Count > 0)
{
.............
.............
}