select * from university_major and p_id = #{pid} and major like #{major} select count(0) from university_major and p_id = #{pid} and major like #{major} insert into university_major (major,major_code,p_id,create_time) values (#{major},#{majorCode},#{pid},GETDATE()) delete university_major where id = #{id} update university_major major=#{major}, major_code=#{majorCode}, where id = #{id} select f.id as f_id , f.major as f_major , s.id as s_id , s.major as s_major from university_major s join university_major f on f.id = s.p_id join university_relate_major r on s.id = r.major_id