oracle去除字符串中的重复值

Question

我有输入数据的要求，例如

Col1 COl2 Col3
A1    2    B
A1    1    A
A1    3    B
B1    1    A
B2    2    B
B2    3    C
B4    4    C
B5    5    A
B6    6    B

需要输出：

Col1 COl2 Col3
A1    2    AB
A1    1    AB
A1    3    AB
B1    1    ABC
B2    2    ABC
B2    3    ABC
B4    4    ABC
B5    5    ABC
B6    6    ABC

尝试过的解决方案：

select col1,col2,listagg(col3,'') within group (order by col3) over(partition by col1)
from tab

查询输出：

Col1 COl2 Col3
A1    2    ABB
A1    1    ABB
A1    3    ABB
B1    1    AABBCC
B2    2    AABBCC
B2    3    AABBCC
B4    4    AABBCC
B5    5    AABBCC
B6    6    AABBCC

有人可以帮忙删除重复的字母吗？

谢谢

Answer 1

您可以使用子查询：

select col1, col2,
       listagg(case when seqnum = 1 then col3 end, '') within group (order by col3) over (partition by col1)
from (select t.*,
             row_number() over (partition by col1, col3 order by col3) as seqnum
      from tab t
     ) t

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