From: | Sergey Konoplev <sergey(dot)konoplev(at)postgresql-consulting(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Thomas Kellerer <spam_eater(at)gmx(dot)net>, pgsql-sql(at)postgresql(dot)org |
Subject: | Re: DELETE using an outer join |
Date: | 2012-07-20 14:13:31 |
Message-ID: | CAL_0b1uDMQuYqpwTEr6JCd5AiwzevCEGJsGiM2DiMoJr_-p=sA@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-sql |
On Fri, Jul 20, 2012 at 5:51 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> DELETE FROM some_table USING some_table AS s
>> WHERE
>> some_table.col1 = s.col1 AND
>> some_table.col2 = s.col2 AND
>> some_table.id < s.id;
>
> No, that's a self-join, which isn't what the OP wanted. You can make it
> work if you self-join on the primary key and then left join to the other
> table, but that's pretty klugy and inefficient.
>
> What was being discussed is allowing people to write directly
>
> DELETE FROM some_table USING some_table LEFT JOIN other_table ...
>
> where the respecification of the table in USING would be understood
> to mean the target table. Right now this is an error case because
> of duplicate table aliases.
Yes, the OP has already pointed me to it. Thank you for your explanation.
--
Sergey Konoplev
a database architect, software developer at PostgreSQL-Consulting.com
http://www.postgresql-consulting.com
Jabber: gray(dot)ru(at)gmail(dot)com Skype: gray-hemp Phone: +79160686204
From | Date | Subject | |
---|---|---|---|
Next Message | ssylla | 2012-07-23 03:04:32 | query two tables using same lookup table |
Previous Message | Tom Lane | 2012-07-20 13:51:15 | Re: DELETE using an outer join |