sql - 从逗号分隔的字符串中删除重复项(Amazon Redshift)

Question

我正在使用Amazon Redshift。

我在该字符串中有一列以逗号分隔的形式存储，类似于Private, Private, Private, Private, Private, Private, United Healthcare。我想使用query从中删除重复项，因此结果应为Private, United Healthcare。我显然从Stackoverflow找到了一些解决方案，并且知道使用正则表达式是可能的。

因此，我尝试使用:

SELECT  regexp_replace('Private, Private, Private, Private, Private, Private, United Healthcare', '([^,]+)(,\1)+', '\1') AS insurances; 

和

SELECT  regexp_replace('Private, Private, Private, Private, Private, Private, United Healthcare', '([^,]+)(,\1)+', '\g') AS insurances; 

还有其他一些正则表达式，但似乎不起作用。有什么办法吗？

Answer 1

试试这个

SELECT  array_agg(DISTINCT insurances) 
FROM (SELECT  regexp_split_to_table('Private, Private, Private, Private, Private, Private, United Healthcare'
              , ',\s+') AS insurances) x;

替代方式

SELECT DISTINCT UNNEST(regexp_split_to_array('Private, Private, Private, Private, Private, Private, United Healthcare', ',\s+')) AS insurances;

检查http://docs.aws.amazon.com/redshift/latest/dg/String_functions_header.html都将因redshift失败，这些都不会将text转换为text[]