顶置sql写法

sql分页，顶置（项目环境内不支持），if后，1代表顶置，0代表底置

 <select id="selectPageList" resultType="com.pig4cloud.pigx.e_ticket.entity.OrderManage">
        SELECT
        id,
        order_no,
        business_no,
        hold_name,
        business_money,
        estimated_premium,
        premium_amount,
        issue_date,
        maturity_date,
        order_status,
        redemption_voucher_status,
        redemption_voucher_path,
        redemption_voucher_date,
        create_time,
        update_time,
        remark
        FROM
        order_manage
        <where>
            ${ew.sqlSegment}
        </where>
        ORDER BY
        IF
        ( order_status = 7 OR order_status = 8, 1, 0 ) ,
        create_time DESC
    </select>