refactor(news): 优化新闻查询和默认新闻更新逻辑

- 修改新闻列表查询默认按创建时间降序排序
- 移除添加和更新新闻时设置默认值的注释代码
- 优化默认新闻更新逻辑，移除冗余的设置操作

ruoyi-modules/ruoyi-system/src/main/java/org/dromara/business/service/impl/NewsInfoServiceImpl.java

@@ -104,7 +104,7 @@ public class NewsInfoServiceImpl implements INewsInfoService {
     private LambdaQueryWrapper<NewsInfo> buildQueryWrapper(NewsInfoBo bo) {
         Map<String, Object> params = bo.getParams();
         LambdaQueryWrapper<NewsInfo> lqw = Wrappers.lambdaQuery();
-        lqw.orderByAsc(NewsInfo::getId);
+        lqw.orderByDesc(NewsInfo::getCreatedAt);
         lqw.eq(StringUtils.isNotBlank(bo.getTitle()), NewsInfo::getTitle, bo.getTitle());
         lqw.eq(StringUtils.isNotBlank(bo.getSummary()), NewsInfo::getSummary, bo.getSummary());
         lqw.eq(bo.getCategoryId() != null, NewsInfo::getCategoryId, bo.getCategoryId());
@@ -141,6 +141,7 @@ public class NewsInfoServiceImpl implements INewsInfoService {
         map.put("positionCode",bo.getPositionCode());
         NewsInfoVo newsInfoListByParam = baseMapper.selectNewsInfoListByParam(map);
         if(newsInfoListByParam!=null){
+           //add.setIsDefault(1L);
            baseMapper.updateDefaultNews(bo.getPositionCode());
         }
         String username = LoginHelper.getUsername();
@@ -171,6 +172,7 @@ public class NewsInfoServiceImpl implements INewsInfoService {
         map.put("positionCode",bo.getPositionCode());
         NewsInfoVo newsInfoListByParam = baseMapper.selectNewsInfoListByParam(map);
         if(newsInfoListByParam!=null){
+            //update.setIsDefault(1L);
             baseMapper.updateDefaultNews(bo.getPositionCode());
         }
         String username = LoginHelper.getUsername();