[Qgis-user] Dissolve keeping all attributes values (concatenation/aggregation)?

[chris hermansen]

Laurent and list,


On Tue, Sep 30, 2025, 07:14 celati Laurent via QGIS-User <
qgis-user at lists.osgeo.org> wrote:

> Dear all,
>
> I work with qgis and postgis. I would like to perform a "dissolve":
>
> https://docs.qgis.org/3.40/en/docs/user_manual/processing_algs/qgis/vectorgeometry.html#dissolve
>
> in keeping/preserving  all attributes values ? For instance : a kind of
> aggregation/concatenation within new "output features" ?
>
> I Saw this post :
>
>  https://www.aproposinfosystems.com/en/about/blog/managing-attributes-postgis-dissolve/
> <https://www.aproposinfosystems.com/en/about/blog/managing-attributes-postgis-dissolve/>
>
> I have tried to reproduce the proposal with my postgis table containing
> several polygons
>
>
>
>
>
>
>
>
>
>
>
>
> *SELECT min(union_v4.max_hierar) as id, array_agg(union_v4.id
> <http://union_v4.id>) as ids, union_v6.geomFROM union_v4, (SELECT
> (ST_Dump(St_multi(ST_Union(geom)))).geom as geom FROM union_v6WHERE
> st_intersects(union_v4.geom, union_v6.geom)GROUP BY union_v6.geom*
>
> But i obtain :
>
>
>
>
>
>
> *ERROR: syntax error at the end of the entryLINE 12: GROUP BY
> union_v6.geom ^ERROR: syntax error at the end of the entrySQL state:
> 42601Characters: 285*
>

I'm on my phone and squinting a bit here but aren't you missing a right
parenthesis? Ending your correlated sub query?

>
>
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