diff --git a/src/main/resources/mapper/CaseExchangeMapper.xml b/src/main/resources/mapper/CaseExchangeMapper.xml
index b1874fc..bb4afac 100644
--- a/src/main/resources/mapper/CaseExchangeMapper.xml
+++ b/src/main/resources/mapper/CaseExchangeMapper.xml
@@ -27,13 +27,18 @@
         a.updated_at,
         c.user_name,
         c.avatar,
-        c.hospital_id
+        c.hospital_id,
+        -- 最新评论时间
+        (
+        SELECT MAX(d.created_at)
+        FROM user_comment_exchange d
+        WHERE d.exchange_id = a.exchange_id
+        ) AS comment_created_at
         FROM (
             SELECT DISTINCT a.exchange_id
             FROM case_exchange a
             LEFT JOIN case_exchange_label b ON a.exchange_id = b.exchange_id
             LEFT JOIN user c ON c.user_id = a.user_id
-            LEFT JOIN user_comment_exchange d ON d.exchange_id = a.exchange_id
             WHERE a.exchange_status = 1
             AND a.delete_status = 0
             <if test="isSelected != null">
@@ -55,13 +60,12 @@
         ) AS result
         JOIN case_exchange a ON result.exchange_id = a.exchange_id
         LEFT JOIN user c ON c.user_id = a.user_id
-        LEFT JOIN user_comment_exchange d ON d.exchange_id = a.exchange_id
         <if test="order != null and !order.isEmpty()">
             ORDER BY
             <foreach item="entry" index="key" collection="order" separator=",">
                 <choose>
                     <when test="key == 'commentCreatedAt'">
-                        d.created_at ${entry}
+                        comment_created_at ${entry}
                     </when>
                     <otherwise>
                         ${key} ${entry}