How to combine rows in Amazon Redshift

Question

I am using Amazon redshift. How do I combine the result of the columns.

If the original rows are:

*ID   Name  Color
----------------
1   John   White
1   John   Black
2   Mark   Blue
2   Mark   Red*

the result should be:

*ID   Name  Color
----------------
1   John   White Black
2   Mark   Blue Red*

Amazon Redshift is based on Postgres. How can a MySQL answer for `group_concat` be relevant? or a "duplicate"? @FancyPants +1 — Paul Maxwell, Nov 09 '17 at 07:25
@Used_By_Already I don't know anything about amazon redshift, but the question was and still is tagged as mysql. — fancyPants, Nov 09 '17 at 09:09
@FancyPants good point, so I changed that. Mark: please only use tags that are relevant to this question. — Paul Maxwell, Nov 09 '17 at 09:30

score 18 · Accepted Answer · answered Nov 09 '17 at 07:28

Redshift provides a function LISTAGG() for what you need

SELECT id, name, LISTAGG(Color,' ') AS Colors
FROM yourtable
GROUP BY id, name

For each group in a query, the LISTAGG aggregate function orders the rows for that group according to the ORDER BY expression, then concatenates the values into a single string. http://docs.aws.amazon.com/redshift/latest/dg/r_LISTAGG.html

SELECT id, name
 , LISTAGG(Color,' ') WITHIN GROUP (ORDER BY name) AS Colors
FROM yourtable
GROUP BY id, name

How to combine rows in Amazon Redshift

1 Answers1