Writing DataReader Rows to Excel File - asp.net

Question

I've got data in SQL Server 2000 and have a HyperLink that goes to a pass-through form whose code-behind will output the data to an Excel file. I've been following this tutorial:
http://www.dzone.com/links/r/export_gridview_to_excelcsv_in_net_using_c.html
I have succeeded in outputting some sample values from the DataReader. First problem I'm encountering is that there is no DataTable Load method in 1.1. I have data coming back via the DataReader but what I need help with is how to create the headers and output them, along with the rows of data, to the Excel file...
Response.Clear();
Response.ClearContent();
Response.ClearHeaders();
Response.Buffer = true;
string attachment
= "attachment;filename=Report_" + DateTime.Now.ToString() + ".xls";
Response.AddHeader("content-disposition", attachment);
Response.Charset = string.Empty;
Response.Cache.SetCacheability(System.Web.HttpCacheability.Public);
Response.ContentType = "application/ms-excel";
DataTable dt = new DataTable();
dt.Columns.Add("Company");
dt.Columns.Add("Address1");
dt.Columns.Add("Address2");
dt.Columns.Add("City");
dt.Columns.Add("State");
dt.Columns.Add("ZipCode");
SqlConnection con = new SqlConnection();
SqlCommand com = new SqlCommand();
con.ConnectionString = "myconnstring";
com.Connection = con;
com.CommandText
= "SELECT DISTINCT Company, Address1, Address2, City, State, ZipCode" +
" FROM Vendor_View";
con.Open();
SqlDataReader dr = com.ExecuteReader();
while(dr.Read())
{
// how to grab and output data to Excel?
}

Answer 1

I myself wrote a blog post about this. Basically there are 3 alternatives. But I recommend this one:
//Make sure you add this reference and have it imported
Using Excel = Microsoft.Office.Interop.Excel;
protected void xlsWorkBook()
{
Excel.Application oXL;
Excel.Workbook oWB;
Excel.Worksheet oSheet;
Excel.Range oRange;
// Start Excel and get Application object.
oXL = new Excel.Application();
// Set some properties
oXL.Visible = true;
oXL.DisplayAlerts = false;
// Get a new workbook.
oWB = oXL.Workbooks.Add(Missing.Value);
// Get the active sheet
oSheet = (Excel.Worksheet)oWB.ActiveSheet;
oSheet.Name = “Customers”;
// Process the DataTable
// BE SURE TO CHANGE THIS LINE TO USE *YOUR* DATATABLE
//DataTable dt = Customers.RetrieveAsDataTable();//commented
DataTable dt = Table;//added
Session["dt"] = dt;//added
int rowCount = 1;
foreach (DataRow dr in dt.Rows)
{
rowCount += 1;
for (int i = 1; i < dt.Columns.Count + 1; i++)
{
// Add the header the first time through
if (rowCount == 2)
{
oSheet.Cells[1, i] = dt.Columns[i - 1].ColumnName;
}
oSheet.Cells[rowCount, i] = dr[i - 1].ToString();
}
}
// Resize the columns
oRange = oSheet.get_Range(oSheet.Cells[1, 1],
oSheet.Cells[rowCount, dt.Columns.Count]);
oRange.EntireColumn.AutoFit();
// Save the sheet and close
oSheet = null;
oRange = null;
oWB.SaveAs(“test.xls”, Excel.XlFileFormat.xlWorkbookNormal,
Missing.Value, Missing.Value, Missing.Value, Missing.Value,
Excel.XlSaveAsAccessMode.xlExclusive,
Missing.Value, Missing.Value, Missing.Value,
Missing.Value, Missing.Value);
oWB.Close(Missing.Value, Missing.Value, Missing.Value);
oWB = null;
oXL.Quit();
// Clean up
// NOTE: When in release mode, this does the trick
GC.WaitForPendingFinalizers();
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
}

Answer 2

If it's simple data, then just emit a CSV file. Excel can be configured to open those pretty easily.
Something like the following would get you started:
response.ContentType = "text/csv";
response.AddHeader("Content-Disposition", "attachment;filename=report.csv;");
response.AddHeader("Pragma", "no-cache");
response.AddHeader("Expires", "0");
// 1. output columns
Boolean addComma = false;
response.Write("\"");
foreach (DataColumn column in _dataToProcess.Columns) {
if (addComma) {
response.Write("\",\"");
} else {
addComma = true;
}
response.Write(column.ColumnName.ToString());
} // foreach column
response.Write("\"");
response.Write(System.Environment.NewLine);
// 2. output data
foreach (DataRow row in _dataToProcess.Rows) {
addComma = false;
response.Write("\"");
foreach (Object value in row.ItemArray) {
// handle any embedded quotes.
String outValue = Convert.ToString(value).Replace("\"", String.Empty);
if (addComma) {
response.Write("\",\"");
} else {
addComma = true;
}
response.Write(outValue);
}
response.Write("\"");
response.Write(System.Environment.NewLine);
} // foreach row