update

mec-biz/src/main/resources/config/mybatis/StudentRegistrationMapper.xml

@@ -1622,7 +1622,7 @@
         SELECT count(sr.id_)
 		from student_registration sr LEFT JOIN sys_user u on sr.user_id_ = u.id_ 
 		LEFT JOIN student s on s.user_id_ = sr.user_id_ LEFT JOIN `subject` sub on sub.id_ = sr.actual_subject_id_
-		LEFT JOIN student_instrument si on si.student_id_ = sr.user_id_
+		LEFT JOIN (select * from student_instrument where id_ in ((select max(id_) from student_instrument group by student_id_))) si on si.student_id_ = sr.user_id_
 		WHERE sr.music_group_status_ = 'NORMAL' 
 		<if test="musicGroupId != null">
 			AND sr.music_group_id_ = #{musicGroupId}