sql - Oracle SQL 从表中获取唯一符号

Question

我有一个带有某些描述的表格。例如:

My_Tableid   description================1    ABC2    ABB3    OPAC4    APEЧ

我需要从所有“描述”列中获取所有唯一符号。结果应该如下所示:

symbol================ABCOPEЧ

它应该适用于所有语言，所以，据我所知，正则表达式无济于事。请帮我。谢谢。

Answer 1

with    cte (c,description_suffix) as
        (
            select  substr(description,1,1)
                   ,substr(description,2)
            from    mytable
            where   description is not null

            union all

            select  substr(description_suffix,1,1)
                   ,substr(description_suffix,2)
            from    cte
            where   description_suffix is not null
        )
select    c
         ,count(*) as cnt
from      cte
group by  c
order by  c 

或

with    cte(n) as
        (
            select      level 
            from        dual 
            connect by  level <= (select max(length(description)) from mytable)
        )
select  substr(t.description,c.n,1) as c
       ,count(*)                    as cnt
from            mytable t
        join    cte c
        on      c.n <= length(description)
group by substr(t.description,c.n,1)
order by c

<小时/>

+---+-----+
| C | CNT |
+---+-----+
| A |   4 |
| B |   3 |
| C |   2 |
| E |   1 |
| O |   1 |
| P |   2 |
| Ч |   1 |
+---+-----+