10 2012 档案

提取表中每个分组的前几条数据
摘要：SELECT 课程, SUM(奖金) AS 奖金FROM ( SELECT 课程, 学号, 成绩 FROM 考试 AS a WHERE ( SELECT COUNT(*) FROM 考试 WHERE 课程 = a.课程 AND 学号 <> a.学号 AND 成绩 > a.成绩 ) < 3 ) AS bGROUP BY 课程 阅读全文
posted @ 2012-10-17 13:06 liyuzhao 阅读(436) 评论(0) 推荐(0)