查询优化

src/main/java/com/teaching/backend/common/ErrorCode.java

@@ -22,6 +22,8 @@ public enum ErrorCode {
     INVALID_ROLE(400010, "角色不存在"),
     MESSAGE_NO_READ(400011, "消息未读，禁止删除！"),
     MESSAGE_NO_EXIT(400012, "消息不存在！"),
+    CONTENT_HAS_NO_KNOWS(400013, "该课程目标暂未关联知识点！"),
+
     NOT_LOGIN_ERROR(40100, "未登录"),
     NO_AUTH_ERROR(40101, "无权限"),
     NOT_FOUND_ERROR(40400, "请求数据不存在"),

src/main/java/com/teaching/backend/service/impl/courses/ObjectiveContentKnowServiceImpl.java

@@ -107,6 +107,9 @@ public class ObjectiveContentKnowServiceImpl extends ServiceImpl<ObjectiveConten
                 new LambdaQueryWrapper<ObjectiveContentKnow>()
                         .eq(ObjectiveContentKnow::getObjectiveContentId, objectiveContentId)
         );
+        if(objectiveContentKnows.isEmpty()){
+            throw new BusinessException(ErrorCode.CONTENT_HAS_NO_KNOWS);
+        }
 
         // 创建并设置ObjectiveContentKnowVO对象的属性
         objectiveContentKnowVO = createObjectiveContentKnowVO(objectiveContentId, objectiveContentKnows);
@@ -120,6 +123,7 @@ public class ObjectiveContentKnowServiceImpl extends ServiceImpl<ObjectiveConten
     }
 
     // 创建ObjectiveContentKnowVO对象，并计算知识点数量、总时间和关联的知识点部分数据
+    // TODO 查询知识点的数据 有优化空间！！！
     private ObjectiveContentKnowVO createObjectiveContentKnowVO(String objectiveOrContentId, List<ObjectiveContentKnow> objectiveContentKnows) {
         ObjectiveContentKnowVO vo = new ObjectiveContentKnowVO();
         vo.setObjectiveOrContent(objectiveOrContentId);