Re: DISTINCT in STRING_AGG

On 28 November 2015 at 18:35, Sterpu Victor <victor(at)caido(dot)ro> 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​