Re: Cast INTEGER to BIT confusion

Hello,

On Tue, 2023-08-15 at 08:49 +0000, [Quipsy] Markus Karg wrote:
>
>
>
> Hello PostgreSQL Community,
>  
> I have 25+ years of experience with some other RDBMS, but I am a
> PostgreSQL starter, so I assume the following is rather a simple
> beginner’s question…:
>  
> I like to store just a single bit but that can be either 1 or 0, so I
> tried to do this:
>  
> CREATE TABLE T (c BIT);
> INSERT INTO T VALUES (1);
> -- I MUST NOT change both lines in any way as these are part of a
> third-party application!
>  
> Unfortunately this tells me:
>  
> column "c" is of type bit but expression is of type integer
>  
> So I logged in as a cluster admin and I tried this:
>  
> CREATE CAST (integer AS bit) WITH INOUT AS IMPLICIT;
>  
> Unfortunately that tells me:
>  
> cast from type integer to type bit already exists
>  
> This is confusing! Apparently PostgreSQL 15.3 comes with the needed
> cast out-of-the-box but it does not apply it? This is confusing!
>  
> What is my fault?
>  
> Thanks!
> -Markus

It works thus:-

postgres 15.4 =# CREATE TABLE T (c BIT);
CREATE TABLE
postgres 15.4 =# insert into T values (B'1');
INSERT 0 1
postgres 15.4 =# select * from t;
c
---
1
(1 row)

See section 9.6 in the doco.

HTH,
Rob