Re: Select Distinct Order By Array_Position - Mailing list pgsql-sql

From David G. Johnston
Subject Re: Select Distinct Order By Array_Position
Date
Msg-id CAKFQuwYroR1Q_+rF6odeDEA5+NLk6TjCYy-yTJUxf+ob7huhdg@mail.gmail.com
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In response to Select Distinct Order By Array_Position  ("Mark Williams" <markwillimas@gmail.com>)
Responses RE: Select Distinct Order By Array_Position  ("Mark Williams" <markwillimas@gmail.com>)
List pgsql-sql
On Mon, Nov 26, 2018 at 12:12 PM Mark Williams <markwillimas@gmail.com> wrote:
> I am ordering by documents.id and it appears in my select list.
[...]
> SELECT DISTINCT documents.id, page_no FROM texts LEFT JOIN documents on documents.id=texts.doc_id WHERE doc_id IN
(26194,2345, 189) AND  (text LIKE '%RIVER%') ORDER BY array_position(ARRAY[26194, 2345, 189]::INTEGER[], documents.id)
 

No, you are not ordering by documents.id, you are ordering by an
expression into which you are passing the documents.id value as one of
its components.

When you use ORDER BY and DISTINCT together you basically are short-handing:

SELECT sq.*
FROM (SELECT DISTINCT ...) AS sq
ORDER BY sq.?

If you want to order by something you have to include it exactly in
the select-list of the inner/distinct query.

In this example, though, you could just "ORDER BY documents.id DESC"...

David J.


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