Returning values with same id as one row

Question

Apologies if this has been answered but trying to word this question was a nightmare to wrap my head around.

Essentially I have a table

and I essentially want a query that returns

post_id	tag_id
15618	6, 109, 659
27248	245, 6, 7, 6499

Have a look at this post https://stackoverflow.com/questions/15847173/concatenate-multiple-result-rows-of-one-column-into-one-group-by-another-column — avikalb, Jul 12 '21 at 00:37
Does this answer your question? [Concatenate multiple result rows of one column into one, group by another column](https://stackoverflow.com/questions/15847173/concatenate-multiple-result-rows-of-one-column-into-one-group-by-another-column) — Jahnavi Paliwal, Jul 12 '21 at 04:19

score 2 · Accepted Answer · answered Jul 12 '21 at 00:44

2

I strongly recommend that you use arrays for this purpose:

select post_id, array_agg(tag_id order by tag_id)
from t
group by post_id;

You can use string_agg(tag_id, ', ' order by tag_id) if you really want a string. In general, though, I find that arrays are much more versatile.

answered Jul 12 '21 at 00:44

Gordon Linoff

Arrays work fine. The format of the result isn't an issue. Just couldn't wrap my head around a way to make the result I wanted happen. I even looked at join and such – Harry Berkley Jul 12 '21 at 00:46

1 Answers1