Thread

1. AW: [HACKERS] Re: Subselects open issue Nr. 5

   Zeugswetter Andreas IZ5 <andreas.zeugswetter@telecom.at> — 1998-02-16T13:19:14Z

   Guess what !
   
   It (Informix 9.12 and DB/2 4.1) says syntax error (at the first comma).
   (Even looked up the Manuals)
   Haha Hihi Hoho. I guess you beat them here Vadim+Bruce+Tom. * hear the cork
   popping ? *
   
   Andreas
   
   PS.: from the logical point of view, I think all rows from x should qualify
   for a where (a,b) not in (empty set)
   because for me NULL is not an empty set, at least it is treated as a value
   in a unique index.
   On the other hand you could argue: the whole set is NULL so a not in ()
   should filter where a not null. 
   I guess no standard has thought about that so far. (Tom ?)
   Summary: I guess it is for us to decide. So I would do exactly as you said
   and return all except (NULL,NULL)
   
   	Vadim B. Mikheev wrote:
   > Meskes, Michael wrote:
   > > 
   > > Yes, and Oracle7 also.
   > > 
   > > I think with NULL values Andreas is right. The whole statement should be
   > > NULLed. That to me is the intuitive behaviour.
   > 
   > Not sure.
   > IMHO, any element, either with defined value or with undefined value
   > (NULL),
   > can't be contained by empty set.
   > 
   > Hm, btw, just curious, what Informix returns for
   > 
   > select * from taba where (a,b) not in (<a select returning no row>);
   > 
   > having in taba tuples with (a,b) in
   > 
   > (NULL, a_value)
   > (NULL, NULL)
   > 
   > ? 
   > Does it return all tuples except for (NULL,NULL) ?
   > 
   > Vadim
   > 
   > 
   
   

2. Re: AW: [HACKERS] Re: Subselects open issue Nr. 5

   Vadim Mikheev <vadim@sable.krasnoyarsk.su> — 1998-02-16T13:53:17Z

   Zeugswetter Andreas SARZ wrote:
   > 
   > Guess what !
   > 
   > It (Informix 9.12 and DB/2 4.1) says syntax error (at the first comma).
   
   ...like SyBase 11... 
   
   > (Even looked up the Manuals)
   > Haha Hihi Hoho. I guess you beat them here Vadim+Bruce+Tom. * hear the cork
   > popping ? *
   > 
   > Andreas
   > 
   > PS.: from the logical point of view, I think all rows from x should qualify
   > for a where (a,b) not in (empty set)
   > because for me NULL is not an empty set, at least it is treated as a value
   > in a unique index.
   > On the other hand you could argue: the whole set is NULL so a not in ()
   > should filter where a not null.
   > I guess no standard has thought about that so far. (Tom ?)
   > Summary: I guess it is for us to decide. So I would do exactly as you said
   > and return all except (NULL,NULL)
   
   I prefer "logical point of view" and vote for Oracle-like behaviour.
   BTW, it's easy to implement...
   
   Vadim
   
   

3. Re: AW: [HACKERS] Re: Subselects open issue Nr. 5

   Thomas Lockhart <lockhart@alumni.caltech.edu> — 1998-02-17T15:41:50Z

   > I prefer "logical point of view" and vote for Oracle-like behaviour.
   > BTW, it's easy to implement...
   
   Sorry I haven't had time to look up the standard. However, in the absence of
   that I vote for the "logical point of view" also. This is better called the
   "intuitive point of view"?
   
                                                     - Tom