| From: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: "SELECT ... FROM DUAL" is not quite as silly as it appears |
| Date: | 2018-10-14 22:11:21 |
| Message-ID: | CAEepm=0W_ycqVAFm8Un04JyBYYfM-xXoV64JS=8A6t2_s+rwNw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Mar 16, 2018 at 4:27 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> We've long made fun of Oracle(TM) for the fact that if you just want
> to evaluate some expressions, you have to write "select ... from dual"
> rather than just "select ...". But I've realized recently that there's
> a bit of method in that madness after all.
We can still make fun of that table. Apparently it had two rows, so
you could double rows by cross joining against it, but at some point
one of them went missing, leaving a strange name behind. Source:
https://en.wikipedia.org/wiki/DUAL_table#History
--
Thomas Munro
http://www.enterprisedb.com
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