GridView Update - Compare values of each row In GridView and Show alert if value is maximum then previous value

Please refer this But you will get more alert popup if each row is having more data than INV_QTY

protected void gvAdjQty_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        SqlConnection conC = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["CIMProRPT01testserverConnectionString"].ConnectionString);

        string InvID = gvAdjQty.DataKeys[e.RowIndex].Values["INV_ID"].ToString();
        string InvLoction = gvAdjQty.DataKeys[e.RowIndex].Values["INV_LOCATION"].ToString();
        string InvQty = gvAdjQty.DataKeys[e.RowIndex].Values["INV_QTY"].ToString();
        TextBox Inv_AdjQty = (TextBox)gvAdjQty.Rows[e.RowIndex].FindControl("Inv_AdjQty");
        if (Convert.ToInt32(Inv_AdjQty.Text) > Convert.ToInt32(InvQty))
        {
            string message = "Your Message";
            System.Text.StringBuilder sb = new System.Text.StringBuilder();
            sb.Append("<script type = 'text/javascript'>");
            sb.Append("window.onload=function(){");
            sb.Append("alert('");
            sb.Append(message);
            sb.Append("')};");
            sb.Append("</script>");
            ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", sb.ToString());
        }
    }

Thank You.