Обсуждение: delete with cascade

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delete with cascade

От
Martín Marqués
Дата:
I was reading the manuals on DELETE and I saw this:

By default DELETE will delete tuples in the table specified and all its
sub-tables. If you wish to only update the specific table mentioned, you
should use the ONLY clause.

I just don't understand what sub-tables means. Does it mean that it will
delete rows on other tables which are referenced with a FOREIGN KEY to the
row which will be deleted?

Saludos... :-)

--
El mejor sistema operativo es aquel que te da de comer.
Cuida tu dieta.
-----------------------------------------------------------------
Martin Marques                  |        mmarques@unl.edu.ar
Programador, Administrador      |       Centro de Telematica
                       Universidad Nacional
                            del Litoral
-----------------------------------------------------------------

Re: delete with cascade

От
Stephan Szabo
Дата:
On Wed, 2 May 2001, [iso-8859-1] Mart�n Marqu�s wrote:

> I was reading the manuals on DELETE and I saw this:
>
> By default DELETE will delete tuples in the table specified and all its
> sub-tables. If you wish to only update the specific table mentioned, you
> should use the ONLY clause.

Any table that inherit from this table.

> I just don't understand what sub-tables means. Does it mean that it will
> delete rows on other tables which are referenced with a FOREIGN KEY to the
> row which will be deleted?

Only if you defined the foreign key with ON DELETE CASCADE.

Re: [SQL] delete with cascade

От
Tom Lane
Дата:
=?iso-8859-1?q?Mart=EDn=20Marqu=E9s?= <martin@bugs.unl.edu.ar> writes:
> I was reading the manuals on DELETE and I saw this:
> By default DELETE will delete tuples in the table specified and all its
> sub-tables. If you wish to only update the specific table mentioned, you
> should use the ONLY clause.

> I just don't understand what sub-tables means.

It means inheritance children, ie, tables you created with INHERIT
from the specified table.

> Does it mean that it will
> delete rows on other tables which are referenced with a FOREIGN KEY to the
> row which will be deleted?

Foreign key deletion is an unrelated feature.

            regards, tom lane