mysql判断当前时间是否在开始与结束时间之间且开始与结束时间允许为空

SELECT * FROM 
表名
WHERE 1=1 
and(start_time is null or start_time<now()) 
and(end_time is null or end_time>now())

<if test="record.startDate != null and record.startDate != '' or record.endDate != null and record.endDate != '' ">
      AND id in
      (select id from rht_product_price where 1=1
      <if test="record.startDate != null and record.startDate != ''">
        and  start_date &lt;= #{record.startDate,jdbcType=VARCHAR}
      </if>
      <if test="record.endDate!= null and record.endDate != ''">
        and end_date &gt;= #{record.endDate,jdbcType=VARCHAR}
      </if>
      )
    </if>