From: Adrian Klaver <adrian.klaver@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: type cast about int to bit
Date: Mon, 6 Feb 2012 17:19:11 -0800
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Cc: zoulx1982 <zoulx1982@163.com>
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On Sunday, February 05, 2012 10:11:12 pm zoulx1982 wrote:
> hi=EF=BC=8C
> there is a problem about type cast that i don't understand, follow is my
> test.
>=20
> postgres=3D# select 10::bit(3);
>  bit
> -----
>  010
> (1 row)
> postgres=3D# select 10::bit varying(3);
> ERROR:  cannot cast type integer to bit varying
> LINE 1: select 10::bit varying(3);
>                  ^
> postgres=3D#
>=20
> my question is why int can cast to bit , i want to know the reason.
> thank you for your timing.

My guess it depends on the  fact that bit types are stored as either char o=
r=20
varchar depending on whether they are bit or bit varying.
In the first case you are basically doing an int-->char, for which there is=
 a=20
built in cast.
In the second case you are doing int-->varchar for which there is not a cas=
t.


=2D-=20
Adrian Klaver
adrian.klaver@gmail.com