asp.net - Gridview fields values does not change on update -

i have gridview , want modify fields on gridview.this fields value not change when click on update button.i tried use postback control problem keep going.how can solve problem?

aspx code

<asp:gridview id="gview" runat="server" autogeneratecolumns="false" enablemodelvalidation="true" gridlines="horizontal" onrowdatabound="gview_rowdatabound" onrowediting="gview_rowediting" onrowupdating="gview_rowupdating" onrowcancelingedit="gview_rowcancelingedit">     <columns>         <asp:boundfield datafield="subcategoryid" headertext="id" insertvisible="false" readonly="true"             sortexpression="subcategoryid" />         <asp:templatefield headertext="category">             <itemtemplate>                 <asp:label id="lblcategory" runat="server"></asp:label>             </itemtemplate>             <edititemtemplate>                 <asp:dropdownlist id="ddlcategory" datavaluefield="categoryid" datatextfield="categoryname" runat="server" />             </edititemtemplate>         </asp:templatefield>         <asp:boundfield datafield="categoryname" headertext="category name" sortexpression="categoryname" />         <asp:commandfield buttontype="link" edittext="edit" headertext="edit"             showeditbutton="true" showheader="false" canceltext="cancel" updatetext="update" />     </columns> </asp:gridview> 

c# code

protected void gview_rowdatabound(object sender, gridviewroweventargs e) {     if (e.row.rowtype == datacontrolrowtype.datarow)     {         label lbl = e.row.findcontrol("lblcategory") label;         dropdownlist ddl = e.row.findcontrol("ddlcategory") dropdownlist;         if ((e.row.rowstate & datacontrolrowstate.edit) > 0)         {             ddl.datasource = loadcategories();             ddl.databind();         }          if (lbl != null)         {             lbl.text = getcategoryname(convert.toint32(gview.datakeys[e.row.rowindex][0]));         }     } }  protected void gview_rowediting(object sender, gridviewediteventargs e) {     gview.editindex = e.neweditindex;     subcategoryload(); }  protected void gview_rowupdating(object sender, gridviewupdateeventargs e) {     int categoryid, subcategoryid;     string categoryname;      dropdownlist ddl = (dropdownlist)gview.rows[e.rowindex].findcontrol("ddlcategory");      subcategoryid = int.parse(gview.rows[e.rowindex].cells[0].text);     categoryid = int.parse(ddl.selectedvalue);     categoryname = gview.rows[e.rowindex].cells[2].text;      gview.editindex = -1;     updatesubcategory(subcategoryid,categoryname,categoryid);     subcategoryload();  }  public void subcategoryload() {     using (sqlconnection conn = new sqlconnection(database.conn))     {         conn.open();         string query = "select * dbo.subcategories";         using (sqldataadapter da = new sqldataadapter(query, conn))         {             datatable dt = new datatable();             da.fill(dt);             gview.datasource = dt;             gview.databind();         }     } }  public int updatesubcategory(int subcategoryid, string categoryname, int categoryid) {     using (sqlconnection conn = new sqlconnection(database.conn))     {         conn.open();         string query = "update dbo.subcategories set categoryid = @categoryid, categoryname = @categoryname subcategoryid = @id";         using (sqlcommand cmd = new sqlcommand(query, conn))         {             cmd.parameters.addwithvalue("@id", subcategoryid);             cmd.parameters.addwithvalue("@categoryname", categoryname);             cmd.parameters.addwithvalue("@categoryid", categoryid);             return (int)cmd.executenonquery();         }     } } 

please check have bind gridview inside

if(!page.ispostback) {  }