มีช่วงเวลาหลายช่วง จะ select ยังไงดีครับ รบกวนหน่อยครับ

private void Form1_Load(object sender, EventArgs e)
        {
            strConn = "Data Source=server;Initial Catalog=testd;User id=dd;Password=dddd;Connection Timeout=9999";
            Conn = new SqlConnection();
            if (Conn.State == ConnectionState.Open)
            {
                Conn.Close();
            }
            Conn.ConnectionString = strConn;
            Conn.Open();
            ShowData();

        }
        public void ShowData()
        {
            string SqlStr = " select  * from testflash ";

            string comstr = SqlStr;
            SqlDataAdapter da = new SqlDataAdapter(comstr, Conn);
            DataTable dt = new DataTable();
            da.Fill(dt);
            da = null;
            Conn.Close();
            Conn = null;

            foreach (DataRow dRow in dt.Rows)
            {



                tmpid = dRow["autoid"].ToString();
                tmpname = dRow["name"].ToString();
                tmpstartdate = Convert.ToInt32(dRow["startdate"]);
                tmpenddate =Convert.ToInt32(dRow["enddate"]);
                tmppathy = dRow["path"].ToString();
                tmppathelse = dRow["pathelse"].ToString();
          
            }