Re: DISTINCT in STRING_AGG

[Geoff Winkless <pgsqladmin@xxxxxxxx>]

On 28 November 2015 at 18:35, Sterpu Victor <victor@xxxxxxxx> wrote:

Can I make a distinct STRING_AGG?

This is my query :

SELECT atjs.id, STRING_AGG(CAST(aqjs1.id AS VARCHAR), ',' ORDER BY aqjs1.to_left) AS children

FROM administration.ad_query_join_select atjs
JOIN administration.ad_query aq ON (aq.id=atjs.id_ad_query)
LEFT JOIN administration.ad_query_join_select aqjs1 ON (aqjs1.id_ad_query = atjs.id_ad_query AND aqjs1.to_left>atjs.to_left AND aqjs1.to_right<atjs.to_right)
LEFT JOIN administration.ad_query_join_select aqjs2 ON (aqjs2.id_ad_query = atjs.id_ad_query AND aqjs2.to_left>atjs.to_left AND aqjs2.to_right<atjs.to_right AND aqjs2.to_left<aqjs1.to_left AND aqjs2.to_right>aqjs1.to_right)
LEFT JOIN administration.ad_query_join_select aqjs3 ON (aqjs3.id_ad_query = atjs.id_ad_query AND aqjs3.to_left<atjs.to_left AND aqjs3.to_right>atjs.to_right)

WHERE aqjs2.id IS NULL AND atjs.id_ad_query = 475543
GROUP BY aq.id, atjs.id
ORDER BY aq.id ASC, atjs.to_left ASC;

 

And "childen" contain doubles. The result is:

id          ; children

1399029;"1399031,1399031"
1399031;"1399032,1399032,1399032,1399033,1399033,1399033"

 

There are doubles because of the join aqjs3 witch is producing this problem.

Can I make it so the children ID's are unique?

 

Well if you can live with losing the to_left ordering, then you could just do

SELECT STRING_AGG(DISTINCT CAST(aqjs1.id​ AS VARCHAR), '') AS children

​

​ ...​

​no?

Geoff​