注意资源利用不然导致资源消耗会很严重

最新推荐文章于 2022-06-17 01:34:29 发布

转载最新推荐文章于 2022-06-17 01:34:29 发布 · 93 阅读

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/toSeeMyDream/p/5537195.html

本文探讨了在使用ORM框架进行数据库操作时的最佳实践，特别是如何正确地开始和管理事务，以及如何优化SQL查询语句。通过示例代码展示了在循环中避免重复开启和提交事务的重要性，并给出了正确的实现方式。

for(Shop s:list) {
            System.out.println(s.getName());
            String sql="select shopId,sum(ele_bank+ele_card+water_card+water_bank+coal_card+coal_bank) as zonghe ,sum(sale_bank+sale_card) as  sale,sum(cigarette_card+cigarette_bank)  as bacco, sum(yidong_card+yidong_bank+dianxin_card+dianxin_bank)  as recharge from hs_shop_items  where  record_time like '%2013-12-12%' and shopId="+s.getId();
            Session officeSession=officeSessionFactory.openSession();
            officeSession.beginTransaction();
            SQLQuery queryOffice=officeSession.createSQLQuery(sql);
            List<ShopTransDTO>  r=queryOffice.addEntity(ShopTransDTO.class).list();
            res.add(r.get(0));
        }

如上图中的

Session officeSession=officeSessionFactory.openSession();
officeSession.beginTransaction();

这个部分放在循环中是错误的

应该这么写:

Session officeSession=officeSessionFactory.openSession();
officeSession.beginTransaction();
for(Shop s:list) {
            System.out.println(s.getName());
            String sql="select shopId,sum(ele_bank+ele_card+water_card+water_bank+coal_card+coal_bank) as zonghe ,sum(sale_bank+sale_card) as  sale,sum(cigarette_card+cigarette_bank)  as bacco, sum(yidong_card+yidong_bank+dianxin_card+dianxin_bank)  as recharge from hs_shop_items  where  record_time like '%2013-12-12%' and shopId="+s.getId();
            SQLQuery queryOffice=officeSession.createSQLQuery(sql);
            List<ShopTransDTO>  r=queryOffice.addEntity(ShopTransDTO.class).list();
            res.add(r.get(0));
}

转载于:https://www.cnblogs.com/toSeeMyDream/p/5537195.html

注意资源利用 不然导致资源消耗会很严重

注意资源利用不然导致资源消耗会很严重