AdminPage -> Save,Update,Delete with Girdview

public partial class CompanyAdmin_Products : System.Web.UI.Page
{
    DAL Obj = new DAL();
    protected void Page_Load(object sender, EventArgs e)
    {
if(!(IsPostBack ))
{
    Obj.Fillgrid(GridView1, "Select PK_ID,Title From Products");
}
if (ViewState["PK_ID"] != null)
{
    btn_edit.Visible = true;
    btn_save.Visible = false;

}
else
{
    btn_save.Visible = true;
    btn_edit.Visible = false;
}

    }
    protected void btn_save_Click(object sender, EventArgs e)
    {
        string image = "";
        if (fileimage.HasFile)
        {
            FileInfo fi = new FileInfo(fileimage.FileName);
            image = Guid.NewGuid().ToString()+ fi .Extension ;

            fileimage .SaveAs(Server .MapPath ("~/Productsimage/")+ image);
        }
        string str = "Products_sp 'I','','" + txttitle.Text + "','" + txt_contents.Value.Replace("'", "''") + "','" + image + "'";
        Obj.insrtfun(str);
        Obj.Fillgrid(GridView1, "Select PK_ID,Title From Products");
        Page.RegisterClientScriptBlock ("V$#WE","<script>alter('Products successfully Added !'),</script>");
        ControlClear();
    }
    protected void btn_edit_Click(object sender, EventArgs e)
    {
        string image = "";
        if (fileimage.HasFile)
        {
            FileInfo fi = new FileInfo(fileimage.FileName);
            image = Guid.NewGuid().ToString() + fi.Extension;
            fileimage.SaveAs(Server.MapPath("~/Productsimage/") + image);

            //string str = "Products_sp 'U','" + txttitle.Text + "','" + txt_contents.Value.Replace("'", "''") + "','" + image + "' where PK_ID='" + ViewState["PK_ID"] + "'";
            //Obj.updatefun(str);
            Obj.getdata("Update Products set Title='" + txttitle.Text + "',Productsdetails='" + txt_contents.Value.Replace ("'", "''") + "',Image='" + image + "' where PK_ID ='" + ViewState["PK_ID"]+ "'"); 
        }
        else
        {
            Obj.getdata("Update Products set Title='" + txttitle.Text + "',Productsdetails='" + txt_contents.Value.Replace("'", "''") + "' where PK_ID ='" + ViewState["PK_ID"] + "'"); 
            //string str = "Products_sp 'U','" + txttitle.Text + "','" + txt_contents.Value.Replace("'", "''") + "' where PK_ID='" + ViewState["PK_ID"] + "'";
            //Obj.updatefun(str);
        }
        Obj.Fillgrid(GridView1, "select PK_ID,Title From Products");
        ControlClear();

    }
    private void ControlClear()
    {

        txttitle.Text = string.Empty;
        txt_contents.Value = string.Empty;
        ViewState["PK_ID"] = null;
    }

    protected void btn_cancel_Click(object sender, EventArgs e)
    {
        ControlClear();
    }

    protected void btn_grd_edit_click(object sender, CommandEventArgs e)
    {
        ViewState["PK_ID"] = e.CommandArgument.ToString();
        DataTable dt = new DataTable();
        dt = Obj.getdata("Select * from Products where PK_ID='" + ViewState["PK_ID"].ToString() + "'");
        txttitle.Text = dt.Rows[0]["Title"].ToString();
        txt_contents.Value = dt.Rows[0]["Productsdetails"].ToString();
        btn_edit.Visible = true;
        btn_save.Visible = false;
    }
    protected void btn_grd_delete_click(object sender, CommandEventArgs e)
    {
        Obj.getdata("Delete from Products where PK_ID='" + e.CommandArgument.ToString() + "'");

        Page.RegisterStartupScript("asas", "<script type='text/javascript'> alert('Record successfully Deleted !');</script>");
        Obj.Fillgrid(GridView1, "select PK_ID,Title From Products");

    }
}