求教sql

[Po_Miao]

有个表tab
AA BB
1 a
2 b
3 c
4 d


查出结果是ab ac ad bc bd cd

[Po_Miao]

引用 1 楼 HJ_daxian 的回复:

如果不考虑效率问题 with t1 as ( select 1 c1,'a' c2 from dual union all select 2 c1,'b' c2 from dual union all select 3 c1,'c' c2 from dual union all s……

不是这样的啊大哥，是一行记录

[Po_Miao]

引用 2 楼 network__yang 的回复:

查询这个有什么用啊

我也不知道什么作用，面试的时候看到

[大明湖畔_帅锅]

如果不考虑效率问题 with t1 as ( select 1 c1,'a' c2 from dual union all select 2 c1,'b' c2 from dual union all select 3 c1,'c' c2 from dual union all select 4 c1,'d' c2 from dual ) select a.c2||b.c2 c1 from t1 a full join t1 b on a.c2 < b.c2 where length(a.c2||b.c2) > length(a.c2) c1 ------------------ 1 ab 2 ac 3 ad 4 bc 5 bd 6 cd

[夏天__]

查询这个有什么用啊

[Po_Miao]

with t1 as ( select 1 c1,'a' c2 from dual union all select 2 c1,'b' c2 from dual union all select 3 c1,'c' c2 from dual union all select 4 c1,'d' c2 from dual ) select wm_concat(a.c2||b.c2) c1 from t1 a join t1 b on a.c2 < b.c2 刚看到一个函数，这样可以查到，感谢上面的提示