如何从 Oracle 中的字符串中获取唯一字符?
Oracle 如何从字符串中获取唯一字符?
How to get the unique characters from a string in Oracle?
假设我有一列数据
CCCXXXCCCCCCCCCCCCCCCCXXCCCCCCCCCCCCCCCCCCCCCCC
我想返回 'CX' 作为唯一字符列表.
and I want to return 'CX' as the list of unique characters.
同样:aaaabbbccccdddaaa ==> abcd , HelloO ==> HeloO
likewise: aaaabbbccccdddaaa ==> abcd , HelloO ==> HeloO
顺序很重要，我希望它们的顺序与它们第一次出现在字符串中的顺序相同.
Order is important, I want them to be in the same order as they first appear in the string.
有没有不使用存储过程的方法?
Is there any way to do it without using stored procedure?
添加更多示例
推荐答案
SELECT SUBSTR(REGEXP_SUBSTR('CCCCXXXCCCCCCCCCCCCCCCCXXCCCCCCCCCCCCCCCCCCCCCCC', '^(.)1*.'), -2, 2) RESULT
FROM DUAL;
它返回CX
这是另一种解决方案:
Select Replace (Wm_Concat (C), ',', '')
From
(Select Substr ('CCCXCCCXXXCCCCCCCCCCCCCCCCXXCCCCCCCCCCCCCCCC', Rownum, 1) C,
Min (Rownum) Rn
From Dual
Connect By Rownum <= Length ( 'CCCXCCCXXXCCCCCCCCCCCCCCCCXXCCCCCCCCCCCCCCCC')
Group By Substr ( 'CCCXCCCXXXCCCCCCCCCCCCCCCCXXCCCCCCCCCCCCCCCC', Rownum, 1)
Order By Rn
) X;
它按出现的顺序返回所有唯一字符.顺便说一句，是的，它看起来很可怕
It returns all the unique chars in order of their occurence. Btw, yes, it looks horrible
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