Re: more on delete from join
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sun, 30 Aug 2009 18:44:35 -0300
Message-ID: <4a9af020$0$23747$9a566e8b_at_news.aliant.net>
>>Kevin Kirkpatrick wrote:
>>
>>>First, there's the relational assignment interpretation, which
>>>attempts to treat this insert into V exactly as if it were an insert
>>>into a base table. My objection to this interpretation was: an INSERT
>>>into a base table can be considered a shorthand for an assignment to a
>>>base table. However, if one attempts to turn the INSERT into V into
>>>an assignment, one gets a view variable on the left hand side and a
>>>relation-value on the right-hand-side, which is clearly a nonsensical
>>>type-violation.
>>
>>Not so. A view is a named relation variable.
Date: Sun, 30 Aug 2009 18:44:35 -0300
Message-ID: <4a9af020$0$23747$9a566e8b_at_news.aliant.net>
Kevin Kirkpatrick wrote:
> On Aug 30, 3:31 pm, Bob Badour <bbad..._at_pei.sympatico.ca> wrote: >
>>Kevin Kirkpatrick wrote:
>>
>>>First, there's the relational assignment interpretation, which
>>>attempts to treat this insert into V exactly as if it were an insert
>>>into a base table. My objection to this interpretation was: an INSERT
>>>into a base table can be considered a shorthand for an assignment to a
>>>base table. However, if one attempts to turn the INSERT into V into
>>>an assignment, one gets a view variable on the left hand side and a
>>>relation-value on the right-hand-side, which is clearly a nonsensical
>>>type-violation.
>>
>>Not so. A view is a named relation variable.
> > Hmm - perhaps I'm confused on the terminology, but I thought a "named > relation variable" was a base relvar, and virtual relvars (aka views) > were "named relation expressions". By this distinction, base relvars > are assigned relation values
No. Both base tables and views are named relation variables. They have to be because their values vary over time. Received on Sun Aug 30 2009 - 23:44:35 CEST