CODEWITHSUNDEEP
sqlpostgresqlaggregate-functions
Curtis
Curtis

Reputation: 55

How can I combine multiple rows into one column using PostgreSQL?

How can I combine multiple results into one column?

For example, my query displays this result:

internaldocid | document id | versionid | title | tagname
1146 | DOC-1146 | 2 | Press Release | tag1
1146 | DOC-1146 | 2 | Press Release | tag2
1146 | DOC-1146 | 2 | Press Release | tag3

I would like it to display this result:

internaldocid | document id | versionid | title | tagname
1146 | DOC-1146 | 2 | Press Release | tag1, tag2, tag3

Here is my SQL:

SELECT
  cmsdocument.internaldocid,
  cmsdocument.documentid,
  cmsdocument.versionid,
  cmsdocversion.title,
  cmstag.tagname
FROM 
  public.cmsobjecttag,
  public.cmstag,
  public.cmsdocument,
  public.cmsdocversion,
  public.cmsuser
WHERE 
  cmsobjecttag.tagid = cmstag.tagid AND
  cmsobjecttag.objectid = cmsdocument.internaldocid AND
  cmsdocument.internaldocid = cmsdocversion.internaldocid AND
  cmsdocument.userid = cmsuser.userid AND
  cmsdocversion.state = 'published' AND
  cmsobjecttag.objecttype = '102';

Any help would be greatly appreciated.

Upvotes: 1

Views: 2705

Answers (1)

Adriano Carneiro
Adriano Carneiro

Reputation: 58595

Since PostgreSQL version 9, this is done simply by using string_agg:

SELECT
  cmsdocument.internaldocid,
  cmsdocument.documentid,
  cmsdocument.versionid,
  cmsdocversion.title,
  string_agg(cmstag.tagname, ',')
FROM 
  public.cmsobjecttag,
  public.cmstag,
  public.cmsdocument,
  public.cmsdocversion,
  public.cmsuser
WHERE 
  cmsobjecttag.tagid = cmstag.tagid AND
  cmsobjecttag.objectid = cmsdocument.internaldocid AND
  cmsdocument.internaldocid = cmsdocversion.internaldocid AND
  cmsdocument.userid = cmsuser.userid AND
  cmsdocversion.state = 'published' AND
  cmsobjecttag.objecttype = '102'
GROUP BY 
  cmsdocument.internaldocid,
  cmsdocument.documentid,
  cmsdocument.versionid,
  cmsdocversion.title

Upvotes: 2

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