排列组合

排列组合

Select *

  From (

Select  translate(sys_connect_by_path(tt,'-'),'A-','A') target

       ,length(translate(sys_connect_by_path(tt,'-'),'A-','A')) sort_key

       ,prn,chl

  From (

Select substr(tar,rnk,1) tt,

       rank() over ( Order By substr(tar,rnk,1)) prn,

       rank() over ( Order By substr(tar,rnk,1)) + 1 chl

  From (Select '&1' tar From Dual ),

       (Select Level rnk From Dual Connect By 1 = 1 And Rownum <= length('&1') )

 Order By tt )

Start With 1 = 1

Connect By prn >= Prior chl )

  Order By sort_key Desc , target ;

 

SQL> /

输入 1 的值 :  abc

输入 1 的值 :  abc

TARGET

-------------------------------------------------------------------------

 

  SORT_KEY        PRN        CHL

---------- ---------- ----------

abc

         3          3          4

 

ab

         2          2          3

 

ac

         2          3          4

 

bc

         2          3          4

 

a

         1          1          2

 

b

         1          2          3

c

         1          3          4