c# - failure in Update of sql table data -

i trying update users details if user want edit his/her information on our system use following code couldn't able it. there no error or exception occur, add watch , code smoothly execute.

public void updateprofile() {      sqlconnection mysql = new sqlconnection(configurationmanager.connectionstrings["blooddonorregistrationconnectionstring"].tostring());     sqlcommand cmd = new sqlcommand("update donor set d_firstname= @fn, d_lastname=@ln, d_phone=@phn, d_city=@ct, d_address=@add d_email='"+session["userid"]+"'", mysql);     cmd.commandtype = commandtype.text;     cmd.parameters.addwithvalue("@fn", textboxfname.text);     cmd.parameters.addwithvalue("@ln", textboxlname.text);     cmd.parameters.addwithvalue("@phn", textboxcellnum.text);     cmd.parameters.addwithvalue("@ct", dropdownlistcity.selecteditem.text);     cmd.parameters.addwithvalue("@add", buttonaddress.text);     mysql.open();     cmd.executenonquery();     mysql.close();     response.redirect("dodashboard.aspx"); } 

please guide , in advance.

session["userid"] object, think d_email column in database of varchar type try using session["userid"].tostring() while using in clause.it work....