update

mec-biz/src/main/java/com/ym/mec/biz/service/impl/ClassGroupServiceImpl.java

@@ -714,7 +714,9 @@ public class ClassGroupServiceImpl extends BaseServiceImpl<Integer, ClassGroup>
         }
         //获取相关老师
         teacherIds.addAll(classGroupDao.findGroupTeacher(groupId));
-        students.addAll(teacherDao.queryTeacherImModel(teacherIds));
+        if(teacherIds.size() > 0){
+            students.addAll(teacherDao.queryTeacherImModel(teacherIds));
+        }
         return students;
     }
 

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

@@ -799,7 +799,7 @@
     </select>
     <select id="queryTeacherImModel" resultMap="com.ym.mec.biz.dal.dao.MusicGroupDao.ImUserModel">
         SELECT su.id_,su.avatar_,
-        CASE WHEN su.username_ IS NULL THEN su.real_name_ ELSE su.username_ END username_
+        CASE WHEN su.username_ IS NULL THEN su.real_name_ END username_
         FROM sys_user su
         WHERE su.id_ IN
         <foreach collection="teacherIds" item="userId" open="(" close=")" separator=",">