<!--查询小于指定日期的第几个记录-->
    <select id="beforeDateNumPrice" resultType="com.mytrade.data.entity.TxdData">
        SELECT
            b.trade_date,
            b.start_price,
            b.max_price,
            b.end_price,
            b.turnover,
            b.variety_code,
            b.variety_name,
            b.id
        FROM
        (
            SELECT
                @rowno :=@rowno + 1 AS rowno,
                a.*
            FROM
                (
                SELECT
                *
                FROM
                txd_data r
                WHERE
                r.trade_date  &lt; #{tradeDate}
                ORDER BY
                trade_date DESC
            ) a,
            (SELECT @rowno := 0) t
        ) b
        WHERE
          b.rowno =  #{beforeNum};
    </select>