Update GridView row and database record on LinkButton Click using C# in ASP.Net

if user click on "Open" button then status should be updated and show as "OPEN" and CLOSING_DATE should be 'NULL' so comp_id visible to user.

namespace gridview_filter
{
    public partial class WebForm2 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                ViewState["Filter"] = "ALL";
                BindGrid();
            }
        }

        private void BindGrid()
        {
            DataTable dt = new DataTable();
            String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
            SqlConnection con = new SqlConnection(strConnString);
            SqlDataAdapter sda = new SqlDataAdapter();
            SqlCommand cmd = new SqlCommand("spx_GetOCMS");
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Parameters.AddWithValue("@Filter", ViewState["Filter"].ToString());
            cmd.Connection = con;
            sda.SelectCommand = cmd;
            sda.Fill(dt);
            GridView1.DataSource = dt;
            GridView1.DataBind();
            DropDownList ddlCountry =
                (DropDownList)GridView1.HeaderRow.FindControl("ddlCountry");
            this.BindCountryList(ddlCountry);
        }

        protected void CountryChanged(object sender, EventArgs e)
        {
            DropDownList ddlCountry = (DropDownList)sender;
            ViewState["Filter"] = ddlCountry.SelectedValue;
            this.BindGrid();
        }

        private void BindCountryList(DropDownList ddlCountry)
        {
            String strConnString = System.Configuration.ConfigurationManager
                        .ConnectionStrings["conString"].ConnectionString;
            SqlConnection con = new SqlConnection(strConnString);
            SqlDataAdapter sda = new SqlDataAdapter();
            SqlCommand cmd = new SqlCommand("select distinct STATUS_NAME" + " from complaint_status");
            cmd.Connection = con;
            con.Open();
            ddlCountry.DataSource = cmd.ExecuteReader();
            ddlCountry.DataTextField = "STATUS_NAME";
            ddlCountry.DataValueField = "STATUS_NAME";
            ddlCountry.DataBind();
            con.Close();
            ddlCountry.Items.FindByValue(ViewState["Filter"].ToString()).Selected = true;
        }

        protected void OnPaging(object sender, GridViewPageEventArgs e)
        {
            GridView1.PageIndex = e.NewPageIndex;
            this.BindGrid();
        }

        protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
        {
            if (e.CommandName == "EditButton")
            {
                int index = Convert.ToInt32(e.CommandArgument);
                GridViewRow row = GridView1.Rows[index];
                Response.Redirect("~/WebForm3.aspx?COMP_ID=" + row.Cells[0].Text);
            }
        }       

        protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                if (e.Row.Cells[8].Text == "Y")
                {
                    (e.Row.FindControl("LinkButton1") as LinkButton).Visible = false;
                }
            }
        }

        protected void LinkButton1_Click(object sender, EventArgs e)
        {

        }

        protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }
    }
}

CREATE TABLE [dbo].[comp_box] (
    [COMP_ID]         INT              NULL,
    [EMP_ID]          NVARCHAR (10)    NULL,
    [COMP_MESSAGE]    NVARCHAR (MAX)   NULL,
    [STATUS_ID]       NVARCHAR (10)    NULL,
    [COMP_LODGE_DATE] DATETIME         NOT NULL,
    [CLOSING_DATE]    DATETIME         NULL,
    [REMARKS]         VARCHAR (255)    NULL,
    [S_GUID]          UNIQUEIDENTIFIER NULL,
    [remote_ip]       NVARCHAR (50)    NULL,
    [who]             NVARCHAR (50)    NULL,
    [user_feedback]   NVARCHAR (255)   NULL,
    [type]            NVARCHAR (255)   NULL,
    [ATTEND_DATE]     DATETIME         NULL,
    [ATTEND_BY]       VARCHAR (255)    NULL
);