Subject: Re: Strange sequences - how to construct?
To: SQL Padawan <sql_padawan@protonmail.com>,
 "pgsql-novice@lists.postgresql.org" <pgsql-novice@lists.postgresql.org>
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From: Alexey M Boltenkov <padrebolt@yandex.ru>
Message-ID: <6b774981-3126-0606-5a17-59fb125a213c@yandex.ru>
Date: Sat, 23 Oct 2021 16:59:19 +0300
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On 10/22/21 22:29, SQL Padawan wrote:
>
> Good afternoon to everybody.
>
> I wish to construct some weird sequences.
>
> 1
> 1
> 2
> 2
> &c.
>
> and with  3 ones, 4 ones... &c.
>
> Now, I know how to do a simple
> 1
> 2
> 3
> 4
>
> using both GENERATE_SERIES and using a RECURSIVE CTE.
>
> What I would like is to be able to construct my specified sequences 
> using *_both_* GENERATE_SERIES *_and_* RECURSIVE CTEs.
>
> Regards,
>
> SQL Padawan!
>
>
>
>
> Sent with ProtonMail <https://protonmail.com/> Secure Email.
>
Or may be you want something strange?

*_both_* GENERATE_SERIES *_and_* RECURSIVE CTEs: with recursive x as ( 
select generate_series(1, 5) x union all select x + 1 from x where x = x 
- 1) select unnest(array[x, x]) x from x;


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    <div class="moz-cite-prefix">On 10/22/21 22:29, SQL Padawan wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:tiUZZ67DYCE5aY4wDAfIXjzlghyf4ndcG2m7wWRd0Rq3rtyhd38iJ9fN2iG088MxWOQtEBlEbsLXzqq-RUYer6rXXfS67pjdwthg8YRIgQU=@protonmail.com">
      <meta http-equiv="content-type" content="text/html; charset=utf-8">
      <div><br>
      </div>
      <div>Good afternoon to everybody.<br>
      </div>
      <div><br>
      </div>
      <div>I wish to construct some weird sequences.</div>
      <div><br>
      </div>
      <div>1<br>
      </div>
      <div>1<br>
      </div>
      <div>2<br>
      </div>
      <div>2<br>
      </div>
      <div>&amp;c.<br>
      </div>
      <div><br>
      </div>
      <div>and with  3 ones, 4 ones... &amp;c.<br>
      </div>
      <div><br>
      </div>
      <div>Now, I know how to do a simple<br>
      </div>
      <div>1<br>
      </div>
      <div>2<br>
      </div>
      <div>3<br>
      </div>
      <div>4<br>
      </div>
      <div><br>
      </div>
      <div>using both GENERATE_SERIES and using a RECURSIVE CTE.<br>
      </div>
      <div><br>
      </div>
      <div>What I would like is to be able to construct my specified
        sequences using *_both_* GENERATE_SERIES *_and_* RECURSIVE CTEs.<br>
      </div>
      <div><br>
      </div>
      <div>Regards,<br>
      </div>
      <div><br>
      </div>
      <div>SQL Padawan!<br>
      </div>
      <div><br>
      </div>
      <div><br>
      </div>
      <div><br>
      </div>
      <div><br>
      </div>
      <div class="protonmail_signature_block">
        <div class="protonmail_signature_block-proton">Sent with <a
            rel="noopener noreferrer" href="https://protonmail.com/"
            target="_blank" moz-do-not-send="true">ProtonMail</a> Secure
          Email.</div>
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      <div><br>
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    </blockquote>
    <p><font size="-2"><tt>Or may be you want something strange?</tt></font></p>
    <p><font size="-2"><tt>*_both_* GENERATE_SERIES *_and_* RECURSIVE
          CTEs: with recursive x as ( select generate_series(1, 5) x
          union all select x + 1 from x where x = x - 1) select
          unnest(array[x, x]) x from x;<br>
        </tt></font><br>
    </p>
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