ORACLE的有关问题

ORACLE的问题
ORACLE在一张表：
NO NAME
1 A
2 B
3 C
4 D


求能显示
AB
AC
AD
BC
BD
CD
的SQL

[解决办法]

SQL code

WITH t AS (SELECT 'a' id FROM dualUNION ALL SELECT 'b' FROM dualUNION ALL SELECT 'c' FROM dualUNION ALL SELECT 'd' FROM dual)SELECT t1.id||t2.id FROM t t1,t t2 WHERE t1.id<t2.id;
[解决办法]
自连接做个迪卡尔集，再比较ASCII码大小。

with t as (
--NO NAME
select 1 as num, 'A' as name from dual
union all
select 2, 'B' from dual
union all
select 3, 'C' from dual
union all
select 4, 'D' from dual
)
select aname || bname from (
select a.num as anum,a.name as aname,b.num as bnum, b.name as bname from t a, t b)
where ascii(aname) < ascii(bname)

ANAME||BNAME  
------------  
AB          
AC          
AD          
BC          
BD          
CD