Web Forms :: How To Save Name Of Uploaded File In Database

I have 1 fileupload control that I can upload file from it below is code :

int count = 0;
if (this.fuppdf.HasFile && !string.IsNullOrEmpty(this.txtarticle.Text))
{
string[] validext = { ".pdf" };
//string ext = System.IO.Path.GetExtension(fuppdf.PostedFile.FileName);
string ext = Path.GetExtension(fuppdf.PostedFile.FileName);

[code].....

and with below code I want save filename (uploaded filename) in database

SqlCommand _cmd = new SqlCommand("Fileuppdf", _cn);
_cmd.CommandType = CommandType.StoredProcedure;
string data = Session["behcode"].ToString();
_cn.Open();
_cmd.Parameters.AddWithValue("@pdf", filename);
_cmd.Parameters.AddWithValue("@Behcode", data);
_cmd.Parameters.AddWithValue("@id", Convert.ToInt32(ViewState["Id"]));

but it make error in this line

_cmd.Parameters.AddWithValue("@pdf", filename);

error===>("The name 'filename' doesn't exist in the current context")

I know that I define filename in 

foreach (string s in files)but I don't know how I can save it name in database