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mysql随机取数_MySQL

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Release： 2016-06-01 13:06:59
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order by RAND() 效率太差.

我的主键为string,网上的高效语句也无法用上.于是自己琢磨了个新的随机取数处理方法. 未做测试.先记录下.

第一步,获取将要获取的数量的总数量.

 string hql_nums = "select COUNT(*) from Table where a='" + a+ "'"; int allnums = MysqlHibernate.GetInstance().getCout(hql_nums);
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第二步.

  Random r = new Random();  int begin = r.Next(allnums - nums); //nums为需要取值数量.防止取数不够
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第三步. 以begin为起点, 取2*nums 条数据.然后对数据进行排序.获取需要的nums条数据.




source：php.cn
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