1.查询表TRENDCHART_DLT中的30条数据，统计字段FRONT01=‘0‘，BACK12=‘0‘的条数
select sum(case when FRONT01=‘0‘ then 1 else 0 end) FRONT01,
sum(case when BACK12=‘0‘ then 1 else 0 end) BACK12
from
(select * from
(select * from TRENDCHART_DLT order by ISSUE desc)
where rownum < 31)
原文：http://www.cnblogs.com/BLE77/p/5166901.html