mybatis最常用的应该是 if test的动态查询，但if语句里只能接收外部传参，而当需要把某字段当成条件去查询时，可以使用case when 语句（这个语法之前只在select用过，一般用来将一些枚举项的id转化为对应的汉字意思）
` rpr.count as count,
rpr.condition as condition_circle

    from  r_point_rule rpr
    LEFT JOIN r_point rp on rpr.id = rp.reason
    <where>
     rpr.is_delete = 0 and rp.is_delete = 0
     and rp.user_id = #{user_id} and
    (case when rpr.circle = 0 then 1=1 when rpr.circle = 1 then  date(rp.creat_time)=current_date
      when rpr.circle = 2 then YEARWEEK(date_format(rp.creat_time,'%Y-%m-%d'),1) = YEARWEEK(now(),1) end )
    </where>

    GROUP BY rpr.id ) as A    on A.id = rpr.id`