Re: :PgSQL: More Queestions

On Wed, 20 Nov 2002, David Wheeler wrote:

> 
> >> Maybe it's just too complex, because, looking at DBD::ODBC's
> >> dbd_preparse(), the handling of literals in the query seems a good 
> >> deal
> >> more straight-forward (though it doesn't appear to handle '\'' or "\""
> >> -- am I reading that right?
> >
> > Nope, it handles " or '.
> >
> >     if (*src == '"' || *src == '\'') {
> >         etc...
> >     }
> 
> It doesn't appear to handle "...""...", though, right? Or am I missing 
> it?
> 

So you have a "". On the first " of the medial "" cluster, the code will
set in_literal to 0, but the very next character is a " so it will set
in_literal right back to '"'.  Now, if there were something between the "s 
it would not be in_literal, see? || am I just serving to confuse?

> PostgreSQL folks, can the same statement return a different number of 
> fields on different executes? I'm guessing yes for something like this, 
> though:
> 
>    CREATE TABLE foo ( bar int, bat, text);
> 
>    SELECT * FROM foo;  -- Returns two fields.
> 
>    ALTER TABLE foo ADD COLUMN fat int;
> 
>    SELECT * FROM foo;  -- Returns three fields.
> 

But using prepared statements:

test=# create table foo (foo integer); 
CREATE TABLE
test=# prepare cached (varchar)  AS select * from foo where foo= $1;
PREPARE
test=# insert into foo values (1);
INSERT 16982 1
test=# execute cached (1);foo 
-----  1
(1 row)

test=# alter table foo add column bar varchar;
ALTER TABLE
test=# execute cached (1);foo 
-----  1
(1 row)

test=# select * from bar;
ERROR:  Relation "bar" does not exist
test=# select * from foo;foo | bar 
-----+-----  1 | 
(1 row)



-r