refactor: 更改子查询为join

src/main/resources/mapper/course/CourseCollectDao.xml

@@ -8,29 +8,45 @@
         SELECT
         MAX(u.update_time) AS produceEndTime,
         c.*,
-            d1.course_details_name AS courseDetailsName,
+        d.course_details_name AS courseDetailsName,
-            d1.course_details_id AS courseDetailsId,
+        d.course_details_id AS courseDetailsId,
-            COUNT(d2.course_details_id) AS courseDetailsCount
+        cd.course_details_count AS courseDetailsCount
         FROM
         course_collect u
-                LEFT JOIN
+        LEFT JOIN course c ON u.course_id = c.course_id
-            course c ON u.course_id = c.course_id
+        LEFT JOIN (
-                LEFT JOIN
+        SELECT
-            course_collect cc1 ON cc1.course_id = u.course_id
+        cc.course_id,
-                AND cc1.classify = 3
+        cc.user_id,
-                AND cc1.user_id = #{userId}
+        d.course_details_name,
-                LEFT JOIN
+        d.course_details_id
-            course_details d1 ON cc1.course_details_id = d1.course_details_id
+        FROM
-                LEFT JOIN
+        course_collect cc
-            course_details d2 ON d2.course_id = c.course_id
+        LEFT JOIN course_details d ON cc.course_details_id = d.course_details_id
+        WHERE
+        cc.classify = 3
+        AND cc.user_id = #{userId}
+        ORDER BY
+        cc.update_time DESC
+        ) AS d ON u.course_id = d.course_id
+        LEFT JOIN (
+        SELECT
+        d.course_id,
+        COUNT(*) AS course_details_count
+        FROM
+        course_details d
+        GROUP BY
+        d.course_id
+        ) AS cd ON c.course_id = cd.course_id
         WHERE
         u.user_id = #{userId}
         AND c.course_id IS NOT NULL
         AND u.classify = #{classify}
         GROUP BY
-            u.course_id, c.course_id
+        u.course_id
         ORDER BY
-            produceEndTime DESC;
+        produceEndTime DESC
+
 
 
         <!--       SELECT