การให้คำสั่ง for ในการวนลูปรูปภาพใครพอจะให้คำแนะนำได้บ้างช่วยชี้แนะที

        StringBuilder sql = new StringBuilder();
        sql.Remove(0, sql.Length);
        sql.Append("SELECT * FROM TB_Counter WHERE C_ID = 1");
        conn.dbconn.Open();
        DataTable dt = new DataTable();
        SqlDataAdapter adap = new SqlDataAdapter(sql.ToString(),conn.dbconn);
        adap.Fill(dt);
        if (dt.Rows.Count > 0)
        {
            int num = dt.Rows[0]["C_num"].ToString().Length;
            Image1.ImageUrl = "";
            for (int i = 0; i < num; i++)
            {
                string a = dt.Rows[0]["C_num"].ToString().Substring(i, 1);
                Image1.ImageUrl += "Images/Counter/" + a + ".gif";
            }
            Image1.ImageUrl += "";
            Response.Write(Image1.ImageUrl);
        }
        conn.dbconn.Close();

	Image img;

	img = new Image ();
	img.ImageUrl  = "Images/Counter/1.gif";

	this.pnlMain1.Controls.Add(img);

	img = new Image ();
	img.ImageUrl  = "Images/Counter/2.gif";

	this.pnlMain1.Controls.Add(img);