feat: Flyway 迁移脚本更新课程包统计数据

V10__update_course_package_stats.sql:
- 根据 lesson 表实际数据更新 usage_count (status != 'cancelled')
- 根据 lesson 表实际数据更新 teacher_count (status = 'completed' 去重教师)

reading-platform-java/src/main/java/com/reading/platform/mapper/CoursePackageMapper.java

@@ -16,6 +16,13 @@ public interface CoursePackageMapper extends BaseMapper<CoursePackage> {
     @Update("UPDATE course_package SET usage_count = usage_count + 1 WHERE id = #{coursePackageId}")
     void incrementUsageCount(@Param("coursePackageId") Long coursePackageId);
 
+    /**
+     * 减少课程包使用次数（课程取消时调用）
+     * @param coursePackageId 课程包 ID
+     */
+    @Update("UPDATE course_package SET usage_count = GREATEST(usage_count - 1, 0) WHERE id = #{coursePackageId}")
+    void decrementUsageCount(@Param("coursePackageId") Long coursePackageId);
+
     /**
      * 更新课程包教师数量（去重统计已完成课程的教师）
      * @param coursePackageId 课程包 ID

reading-platform-java/src/main/java/com/reading/platform/service/impl/LessonServiceImpl.java

@@ -174,6 +174,7 @@ public class LessonServiceImpl extends ServiceImpl<LessonMapper, Lesson>
     public void startLesson(Long id) {
         Lesson lesson = getLessonById(id);
         lesson.setStatus(LessonStatus.IN_PROGRESS.getCode());
+        lesson.setStartDatetime(LocalDateTime.now());
         lessonMapper.updateById(lesson);
         log.info("课程开始：id={}", id);
     }
@@ -183,6 +184,7 @@ public class LessonServiceImpl extends ServiceImpl<LessonMapper, Lesson>
     public void completeLesson(Long id) {
         Lesson lesson = getLessonById(id);
         lesson.setStatus(LessonStatus.COMPLETED.getCode());
+        lesson.setEndDatetime(LocalDateTime.now());
         lessonMapper.updateById(lesson);
         log.info("课程完成：id={}", id);
 
@@ -200,6 +202,12 @@ public class LessonServiceImpl extends ServiceImpl<LessonMapper, Lesson>
         lesson.setStatus(LessonStatus.CANCELLED.getCode());
         lessonMapper.updateById(lesson);
         log.info("课程取消：id={}", id);
+
+        // 更新课程包统计：使用次数 -1（取消的课程不计入使用）
+        if (lesson.getCourseId() != null) {
+            coursePackageMapper.decrementUsageCount(lesson.getCourseId());
+            log.info("课程包使用次数 -1: courseId={}", lesson.getCourseId());
+        }
     }
 
     @Override

reading-platform-java/src/main/resources/db/migration/V10__update_course_package_stats.sql

@@ -0,0 +1,37 @@
+-- -----------------------------------------------------
+-- V10: 更新课程包统计数据
+-- 说明：根据 lesson 表实际数据更新 course_package 的 usage_count 和 teacher_count
+-- 时间：2026-03-20
+-- -----------------------------------------------------
+
+-- 1. 更新 usage_count：统计 status != 'cancelled' 的课程数
+UPDATE course_package cp
+SET usage_count = (
+    SELECT COUNT(*)
+    FROM lesson l
+    WHERE l.course_id = cp.id
+    AND l.status != 'cancelled'
+    AND l.deleted = 0
+)
+WHERE cp.deleted = 0;
+
+-- 2. 更新 teacher_count：统计 status = 'completed' 的课程中去重教师数
+UPDATE course_package cp
+SET teacher_count = (
+    SELECT COUNT(DISTINCT l.teacher_id)
+    FROM lesson l
+    WHERE l.course_id = cp.id
+    AND l.status = 'completed'
+    AND l.teacher_id IS NOT NULL
+    AND l.deleted = 0
+)
+WHERE cp.deleted = 0;
+
+-- 3. 处理 NULL 值，确保字段为 0 而不是 NULL
+UPDATE course_package cp
+SET usage_count = 0
+WHERE usage_count IS NULL AND deleted = 0;
+
+UPDATE course_package cp
+SET teacher_count = 0
+WHERE teacher_count IS NULL AND deleted = 0;