听说Sql Server和MySql中有Top关键字，可以返回排序记录的前N条记录，如select top 10 * from table_name order by col_name，我想Oracle也必定有类似的功能，只是Oracle没有Top关键字，而是使用Rownum关键字。
To retrieve the Top N records from a query, you can use the following syntax:
SELECT *
FROM (your ordered query) alias_name
WHERE rownum <= Rows_to_return
ORDER BY rownum;按照上边的语法，写出如下的查询语句：
select * from (select rownum from gzl_流程流转状态 order by 流程实例编号 ) kk where rownum<=10 order by rownum;
即将 gzl_流程流转状态 表按流程实例编号排序后再返回其前10行，要返回最后10行只需要降序排序即可，这一点很容易想到。kk是子查询的别名，也可以不写。
SELECT title, art_id, reader_count
FROM (SELECT title, art_id, reader_count
FROM article
WHERE (sys_cat <> 'NEWS') AND (eff_status = 'A')
ORDER BY reader_count DESC)
WHERE (ROWNUM <= 3)
ORDER BY ROWNUM ASC
