Обсуждение: A mistake generates strange result

Just for PgSQL's development group think about....

I made a mistake typing a query that generates a strange result (Very strange).

The query: select text('12345678'::float8);

It returns a date in datetime format !!!!!!

If you use: select ('12345678'::float8)::text;        everything runs well.

How do I unsubscribe?

Sorry to post this to the entire list, but it your messages don't
have unsubscription info at the bottom, and the person who subscribed
(ckhui@school.net) isn't a valid user here (I am the postmaster).

-Joel Henderson
 postmaster@school.net

I have a parallel inheritance going on,
so I was wondering if there was a way
to re-name a derived column?  This would
make my design clearer.
-----------------

CREATE TABLE B
( NAME VARCHAR(10) );

CREATE TABLE C
( ... ) INHERITS(B);

CREATE TABLE X
(
   A VARCHAR(10),
   B VARCHAR(10),
   CONSTRAINT FOREIGN KEY (B) REFERENCES B(OID)
);

CREATE TABLE Y
(  B AS C,              /* Syntatic Sugar */
   D VARCHAR(10),
   CONSTRAINT FOREIGN KEY (C) REFERENCES C(OID)
) INHERITS(X)


Here, I've added the syntax "AS" to show that
column A in table X, is called B in the
derived table Y.

Thank you for your thoughts.

:) Clark Evans

    Hi !

"Ricardo J.C.Coelho" <pulsar@truenet-ce.com.br> writes:
> Just for PgSQL's development group think about....
> I made a mistake typing a query that generates a strange result
> (Very strange).

> The query: select text('12345678'::float8);
> It returns a date in datetime format !!!!!!

    I didn't found any function of name "text" that converts
float8 to text. So I think Postgres made an implicit cast of the data
to datatime. So: String->Float8->DateTime->Text. Stranger : I didn't
found any function to cinvert float to text !

> If you use: select ('12345678'::float8)::text;        everything runs well.

    Here, you made an explicit cast, without the use of any
function. So your data is casted well.

    Hope this helps !

Stéphane Dupille ha scritto:

        Hi !

"Ricardo J.C.Coelho" <pulsar@truenet-ce.com.br> writes:
> Just for PgSQL's development group think about....
> I made a mistake typing a query that generates a strange result
> (Very strange).

> The query: select text('12345678'::float8);
> It returns a date in datetime format !!!!!!

        I didn't found any function of name "text" that converts
float8 to text. So I think Postgres made an implicit cast of the data
to datatime. So: String->Float8->DateTime->Text. Stranger : I didn't
found any function to cinvert float to text !

> If you use: select ('12345678'::float8)::text;        everything runs well.

        Here, you made an explicit cast, without the use of any
function. So your data is casted well.

        Hope this helps !

hygea=> select text('12345678'::float8);
text
----------------------
2000-05-22 23:21:18+02

but if you create the function like:

create function text(float8) returns text as
'
begin
        return $1;
end;
' language 'plpgsql';
CREATE

select text('12345678.2'::float8);
      text
----------
12345678.2
(1 row)
 

                               - Jose' -

And behold, I tell you these things that ye may learn wisdom; that ye may
learn that when ye are in the service of your fellow beings ye are only
in the service of your God.                - Mosiah 2:17 -