c# - how to work with multiple datakeys in gridview? -

i created gridview multiple (two) datakeys , tried extract datakey values in code included below. when load gridview, row["booktaxid"] gives correct id being used. while i'm extracting value gridview datakeys code same column returns "1". can me? code-->

gridview:- <asp:gridview runat="server" id="taxgv" datakeynames="id, booktaxid" autogeneratecolumns="false" ondatabound="taxgv_databound" onrowcommand="taxgv_rowcommand" cssclass="table table-bordered table-hover table-responsive" showfooter="true">  loadinggridview taxgv:- public void loadtaxgridview_table()     {         double value = 0;         int bkid = convert.toint32(bookid);         string str = configurationmanager.connectionstrings["constr"].connectionstring;         sqlconnection con = new sqlconnection(str);         con.open();         sqlcommand cmd = new sqlcommand("select b.booktaxid booktaxid, b.taxid id, t.name name, b.taxvalue value bookingtax b inner join taxes t on t.id = b.taxid b.bookingid=@bookingid , b.is_delete=0", con);         cmd.parameters.addwithvalue("@bookingid", bkid);         datatable dt_booktax = new datatable();         sqldatareader reader = cmd.executereader();         dt_booktax.load(reader);         con.close();         foreach(datarow row in dt_booktax.rows)         {             int id = convert.toint32(row["booktaxid"]);//this gives correct value of booktaxid             value = convert.todouble(row["value"]);             total_tax_amount += (temp_amount * value / 100);          }          getparameters_bookingtax(value);          datarow dr = null;         dr = dt_booktax.newrow();         dr["booktaxid"] = 0;         dr["id"] = 0;         dr["name"] = string.empty;         dr["value"] = 0;         dt_booktax.rows.add(dr);          viewstate["booktax_table"] = dt_booktax;         taxgv.datasource = dt_booktax;         taxgv.databind();         taxgv.rows[taxgv.rows.count - 1].visible = false;      } 

updaing table through gridview taxgv:-

public void edit_booking_tax()     {         int bkid = convert.toint32(bookid);         string str = configurationmanager.connectionstrings["constr"].connectionstring;         sqlconnection con = new sqlconnection(str);         con.open();         foreach(gridviewrow row in taxgv.rows)         {             int rowindex = row.rowindex;             int booktaxid = convert.toint32(taxgv.datakeys[rowindex].values["booktaxid"]);             //this booktaxid gives value=1;              label lb_taxvalue = (label)row.cells[1].findcontrol("item_value");             hiddenfield hf_taxid = (hiddenfield)row.cells[2].findcontrol("hf_taxid");             if (lb_taxvalue.text != "0")             {                 sqlcommand cmd = new sqlcommand("update bookingtax set bookingid=@bookingid, taxid=@taxid, taxvalue=@taxvalue, modifiedby=@modifiedby, modifieddate=@modifieddate booktaxid=@booktaxid", con);                 cmd.parameters.addwithvalue("@bookingid", bkid);                 cmd.parameters.addwithvalue("@taxid", convert.toint32(hf_taxid.value));                 cmd.parameters.addwithvalue("@taxvalue", convert.todouble(lb_taxvalue.text));                 cmd.parameters.addwithvalue("@modifiedby", session["id"].tostring());                 cmd.parameters.addwithvalue("@modifieddate", datetime.now);                 cmd.parameters.addwithvalue("@bookingid", bkid);                 cmd.parameters.addwithvalue("booktaxid", booktaxid);                 cmd.executenonquery();             }         }         con.close();     } 

try changing line

int booktaxid = convert.toint32(taxgv.datakeys[rowindex].values["booktaxid"]); 

to

int booktaxid = convert.toint32(taxgv.datakeys[rowindex].values[1]); 

as far remember should able access values of datakeys based on position similar accessing array particular row.