select * from question_wrong and user_id = #{userId} and km = #{km} select q1.id,q2.create_time from question_info q1 join question_wrong q2 on q1.id = q2.question_id and q2.user_id = #{userId} and q2.km = #{km} order by q2.create_time select count(1) from question_info q1 join question_wrong q2 on q1.id = q2.question_id and q2.user_id = #{userId} and q2.km = #{km}