在 Postgresql 中对字符串中的逗号分隔值进行排序

问题描述

有什么办法可以按升序或降序对字符串的值重新排序吗？

即 值：u,a,c,a 到 a,u

解决方法

您可以通过在字符串上取消嵌套来打破多行中的值，然后对其进行分组来实现这一点

按 ASC 顺序获取结果

WITH cte AS (
        SELECT id,unnest(string_to_array(str,',')) as str
        FROM test_string
        order by 1,2 
     )
select ID,string_agg(str,') final_string  
from cte 
group by id
order by final_string ;

按 DESC 顺序获取结果

WITH cte AS (
        SELECT id,2 desc
     )
select ID,') final_string  
from cte 
group by id
order by final_string desc;

您可以使用以下代码重现该场景。

    drop table if exists test_string;
create table test_string (id integer,str varchar(100));

insert into test_string (id,str) values (1,'q,w,r');
insert into test_string (id,str) values (2,'a,e,c');
insert into test_string (id,str) values (3,z,e');       
        
-- Getting results in ASC order
WITH cte AS (
        SELECT id,') final_string  
from cte 
group by id
order by final_string ;

-- Getting results in DESC order
WITH cte AS (
        SELECT id,') final_string  
from cte 
group by id
order by final_string desc;