SQL查询实现，记录排序编号

对数据表的查询实现（股票涨幅SQL查询），数据库记录排序编号，按照顺序计算相邻两行数据的相关属性值：

set @count = 0;
set @count1 = 0;
select b.Date, c.Date, b.`Close`, ifnull(c.`Close`, 0) as `start`, (b.`Close`-IFNULL(c.`Close`,0))/IFNULL(c.`Close`,b.`Close`-IFNULL(c.`Close`,0))*100 as increase from
(select (@count := @count + 1) as rownum , `Date`, `Code`, `Close`
from Stock as a ORDER BY a.code, a.Date) as b LEFT JOIN
(select (@count1 := @count1 + 1) as rownum , `Date`, `Code`, `Close`
from Stock as a ORDER BY a.code, a.Date) as c
on b.Code=c.Code and b.rownum-1=c.rownum