static变量的一个问题
代码如下:
 public static String photoId="";    protected void Page_Load(object sender, EventArgs e)
    {
        lblUserName.Text = Session["UserName"].ToString();
        if (!IsPostBack)
        {
            this.GetFileData();
        }
    }

    public void GetFileData()
    {
        using (OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("photo.mdb")))
        {
            conn.Open();
            OleDbDataAdapter os = new OleDbDataAdapter("select * from tb_photo where photoUser='" + Session["UserName"].ToString() + "' order by id desc", conn);
            DataSet ds = new DataSet();
            os.Fill(ds);
            if (ds.Tables[0].Rows.Count > 0)
            {
                GridView1.DataSource = ds.Tables[0];
                GridView1.DataKeyNames = new String[] { "ID" };
                GridView1.DataBind();
            }
        }

        using (OleDbConnection conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("photo.mdb")))
        {
            conn.Open();
            OleDbDataAdapter oa = new OleDbDataAdapter("select * from tb_photo order by id desc",conn);
            
            DataSet ds = new DataSet();
            oa.Fill(ds);
            if (ds.Tables[0].Rows.Count > 0)
            {
                photoId = (Convert.ToInt32(ds.Tables[0].Rows[0][0]) + 1).ToString();
            }
            else