From: | David Salisbury <salisbury(at)globe(dot)gov> |
---|---|
To: | John R Pierce <pierce(at)hogranch(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: exclusive OR possible within a where clause? |
Date: | 2011-10-17 19:40:32 |
Message-ID: | 4E9C84B0.6010509@globe.gov |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
On 10/17/11 1:19 PM, John R Pierce wrote:
> On 10/17/11 12:15 PM, David Salisbury wrote:
>> <> is the same as !=, which is
>> different than the fabled XOR I was hoping for. In fact
>> they would never equal.
>
> F != F -> false
> F != T -> true
> T != F -> true
> T != T -> false
>
>
> how is that different than XOR, assuming the arguments are booleans ?
>
>
Perhaps what I'm hoping to do got munged. In essence it's equivalent of..
create table test ( something numeric );
insert into test values ( 1 );
insert into test values ( 2 );
select * from test where ( something = 1.5 + .5 ) or ( something = 1.5 - .5 );
something
-----------
1
2
(2 rows)
select * from test where ( something = 1.5 + .5 ) <> ( something = 1.5 - .5 );
something
-----------
1
2
(2 rows)
( which is of course equivalent of where something = 1 or something = 2 )
In my fabled XOR, I'd get the first one it matched, say something = 1, and the
something = 2 would then be ignored/dropped.
Dave
From | Date | Subject | |
---|---|---|---|
Next Message | John R Pierce | 2011-10-17 20:12:07 | Re: exclusive OR possible within a where clause? |
Previous Message | Ken Tanzer | 2011-10-17 19:21:26 | Re: exclusive OR possible within a where clause? |