Oracle中的sql在DB2中不知道怎么转换

select a.x xs, coalesce(b.y, 0) y from (select to_char(to_date(?, 'yyyy-MM-dd') + (level - 1), 'yyyy-MM-dd') x from sysibm.sysdummy1 connect by trunc(to_date(?, 'yyyy-MM-dd') + level - 1) <=trunc(to_date(?, 'yyyy-MM-dd'))) a,(select t.x, count(1) y from (select to_char(a.x, 'yyyy-MM-dd') x from (select h.createdate x from wfl_taskinfo_his h where h.tradeno in ('000040','000080') and to_char(h.createdate, 'yyyy-MM-dd') >= ? and to_char(h.createdate, 'yyyy-MM-dd') <= ?) a) t group by t.x) b where b.x(+) = a.x order by a.x asc
这里面的connect by level在DB2中不支持,请问怎么转换啊?

可以参考下
http://www.ibm.com/developerworks/cn/data/library/techarticles/dm-0510rielau/

看的不是很懂啊,我这里面最主要就是connect by和伪列level不知道怎么在DB2中转换