refactor: 更改子查询为join

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

@@ -8,56 +8,58 @@
     </update>
     <select id="selectCourse" resultType="Map">
         SELECT
-        c.classify_id AS classifyId,
-        c.course_id AS courseId,
-        c.course_label AS courseLabel,
-        c.create_time AS createTime,
+        c.classify_id as classifyId,
+        c.course_id as courseId,
+        c.course_label as courseLabel,
+        c.create_time createTime,
         c.details,
         c.img,
-        c.banner_img AS bannerImg,
+        c.banner_img as bannerImg,
         c.status,
-        c.is_delete AS isDelete,
-        c.msg_type AS msgType,
-        c.msg_url AS msgUrl,
-        c.pay_num AS payNum,
+        c.is_delete as isDelete,
+        c.msg_type msgType,
+        c.msg_url as msgUrl,
+        c.pay_num as payNum,
         c.price,
-        c.wholesale_price AS wholesalePrice,
-        c.is_over AS isOver,
+        c.wholesale_price as wholesalePrice,
+        c.is_over as isOver,
         c.title,
-        c.is_price AS isPrice,
-        c.title_img AS titleImg,
-        c.update_time AS updateTime,
-        cc.classification_name AS classificationName,
-        c.course_type AS courseType,
-        c.banner_id AS bannerId,
-        b.name AS bannerName,
-        0 AS viewCounts,
-        c.dy_img_id AS dyImgId,
-        c.dy_course_id AS dyCourseId,
-        c.wx_course_id AS wxCourseId,
-        c.wx_show AS wxShow,
-        c.dy_show AS dyShow,
+        c.is_price as isPrice,
+        c.title_img as titleImg,
+        c.update_time as updateTime,
+        cc.classification_name as classificationName,
+        c.course_type as courseType,
+        c.banner_id as bannerId,
+        b.name as bannerName,
+        0 as viewCounts,
+        c.dy_img_id as dyImgId,
+        c.dy_course_id as dyCourseId,
+        c.wx_course_id as wxCourseId,
+        c.wx_show as wxShow,
+        c.dy_show as dyShow,
         c.sort,
-        ROUND(10000 * RAND(), 0) AS goodNum,
-        d.courseDetailsCount,
-        NULL AS courseDetailsName,
-        NULL AS courseDetailsId,
-        ROUND(10000 * RAND(), 0) AS weekGoodNum,
-        0 AS isRecommend
+        round(10000*rand(),0) as goodNum,
+        cd.course_details_count as courseDetailsCount,  -- Replaced subquery with left join count
+        null AS courseDetailsName,
+        null AS courseDetailsId,
+        round(10000*rand(),0) as weekGoodNum,
+        0 as isRecommend
         FROM
         course AS c
-        LEFT JOIN
-        course_classification AS cc ON c.classify_id = cc.classification_id
-        LEFT JOIN
-        banner AS b ON b.id = c.banner_id
-        LEFT JOIN
-        (SELECT course_id, COUNT(*) AS courseDetailsCount
-        FROM course_details
-        GROUP BY course_id) AS d ON c.course_id = d.course_id
-        LEFT JOIN
-        (SELECT course_id FROM course_details WHERE good = 1) AS gd ON c.course_id = gd.course_id
+        LEFT JOIN course_classification AS cc ON c.classify_id = cc.classification_id
+        LEFT JOIN banner AS b ON b.id = c.banner_id
+        LEFT JOIN (
+        SELECT
+        course_id,
+        COUNT(*) as course_details_count
+        FROM
+        course_details
+        GROUP BY
+        course_id
+        ) AS cd ON c.course_id = cd.course_id
         WHERE
-        c.is_delete = 0
+        1 = 1
+        AND c.is_delete = 0
         <if test='null != wxShow and wxShow==1'>
             AND c.wx_show = #{wxShow}
         </if>
@@ -86,7 +88,7 @@
             AND c.is_over = #{over}
         </if>
         <if test="isRecommend != null and isRecommend != -1">
-            AND gd.course_id IS NOT NULL
+            AND c.course_id IN (SELECT course_id FROM course_details WHERE good = 1)
         </if>
         <if test="status != null and status != 0">
             AND c.status = #{status}
@@ -108,7 +110,8 @@
         </if>
         <if test="sort != null and sort == 2">
             ORDER BY weekGoodNum DESC
-        </if>;
+        </if>
+
 
 
         <!--