17:05:05 SQL> select * from b;AA DD
-- --
A1 D1
A1 D2
A2 D3已用时间: 00: 00: 00.00
17:05:13 SQL> select aa,dd from
17:05:24 2 (select aa,decode((select count(*) from b d where d.aa=c.aa),1,dd,
dd||'等') dd from b c) a
17:05:24 3 where rowid=(select min(rowid) from b where a.aa=b.aa);AA DD
-- ----
A1 D1等
A2 D3已用时间: 00: 00: 00.16
-- --
A1 D1
A1 D2
A2 D3已用时间: 00: 00: 00.00
17:05:13 SQL> select aa,dd from
17:05:24 2 (select aa,decode((select count(*) from b d where d.aa=c.aa),1,dd,
dd||'等') dd from b c) a
17:05:24 3 where rowid=(select min(rowid) from b where a.aa=b.aa);AA DD
-- ----
A1 D1等
A2 D3已用时间: 00: 00: 00.16
decode(max((select count(tb1.aa) from tb tb1 where tb1.aa=ta.aa group by tb1.aa)),1,' ','等') D
from ta,tb
where tb.aa=ta.aa
group by ta.aa
/
2 decode(max((select count(tb1.aa) from tb tb1 where tb1.aa=ta.aa group by tb1.aa)),1,' ','等') D
3 from ta,tb
4 where tb.aa=ta.aa
5* group by ta.aa
SQL> /AA DD
---------- ------------
a1 d2等
a2 ee
---------- ---------- ----------
a1 b1 c1
a2 b2 c2SQL> select * from tb;AA DD
---------- ----------
a1 d1
a1 d2
a2 ee
from a,b
where a.aa=b.aa
group by a.aa,b.dd