2dropdown list filling in the grid view

Question

 protected void btnadd_Click(object sender, EventArgs e)

    {

        int rowIndex = 0;

        string selectquery = "select   visitorid,VisitorType from VisitorDetails Order By   VisitorType";

        dt = SqlHelper.Instance.GetTableByQuery(selectquery);

        string selectquery1 = "select  Id,ArtistsName from MehndiPortraitDetails Order By  ArtistsName";

        dt1 = SqlHelper.Instance.GetTableByQuery(selectquery1);

        if (ViewState["CurrentTable"] != null)

        {

            DataTable dtCurrentTable = (DataTable)ViewState["CurrentTable"];

            DataRow drCurrentRow = null;

            if (dtCurrentTable.Rows.Count > 0)

            {

                for (int i = 1; i <= dtCurrentTable.Rows.Count; i++)

                {

                    DropDownList ddlmehndi =

                   (DropDownList)Gridmehndi.Rows[rowIndex].Cells[0].FindControl("ddlmehndi");

                    DropDownList ddlArtist =

                  (DropDownList)Gridmehndi.Rows[rowIndex].Cells[1].FindControl("ddlArtist");

                    drCurrentRow = dtCurrentTable.NewRow();

                    TextBox Texttotalamount =

                  (TextBox)Gridmehndi.Rows[rowIndex].Cells[2].FindControl("txtamount");

                    dtCurrentTable.Rows[i - 1]["Selected List"] = ddlmehndi.SelectedValue;

                    dtCurrentTable.Rows[i - 1]["Name of the Artist"] = ddlArtist.SelectedValue;

                 

                    dtCurrentTable.Rows[i - 1]["Amount Paid"] = Texttotalamount.Text;

                    rowIndex++;

                }

                dtCurrentTable.Rows.Add(drCurrentRow);

                ViewState["CurrentTable"] = dtCurrentTable;

                Gridmehndi.DataSource = dtCurrentTable;

                Gridmehndi.DataBind();

            }

        }

        else

        {

            Response.Write("ViewState is null");

        }

        foreach (GridViewRow gvrow in Gridmehndi.Rows)

        {

            DropDownList ddlmehndi = (DropDownList)gvrow.FindControl("ddlmehndi");

            ddlmehndi.DataTextField = " VisitorType";

            ddlmehndi.DataValueField = "Visitorid";

            ddlmehndi.DataSource = dt;

            ddlmehndi.DataBind();

        }

     

 

        foreach (GridViewRow gvrow1 in Gridmehndi.Rows)

        {

            DropDownList ddlArtist = (DropDownList)gvrow1.FindControl("ddlArtist");

            ddlArtist.DataTextField = "ArtistsName";

            ddlArtist.DataValueField = "id";

            ddlArtist.DataSource = dt1;

            ddlArtist.DataBind();

        }

      

        SetPreviousData();

    }