Re: Removing trailing zeros (decimal places) from a numeric (pre trim_scale()) with unexpected behaviour

From: Erik Wienhold <ewie(at)ewie(dot)name>
To: magog002(at)web(dot)de, pgsql-general(at)lists(dot)postgresql(dot)org
Subject: Re: Removing trailing zeros (decimal places) from a numeric (pre trim_scale()) with unexpected behaviour
Date: 2023-03-15 16:50:40
Message-ID: 1053334888.488227.1678899040820@office.mailbox.org
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> On 15/03/2023 14:51 CET magog002(at)web(dot)de wrote:
>
> I want to remove not needed decimal places / trailing zeros from a numeric.
> I know this can be done starting PG >=13 with TRIM_SCALE(numeric) which would
> solve my issue (with an additional CAST to TEXT at the end). Unfortunately
> the production database is still running with PostgreSQL 12.x and this is
> something I currently can't change.
>
> So to get rid of the not needed decimal places I tried TO_CHAR(..., 'FM....')
> in combination with TRUNC() as shown below with examples. This does not remove
> the decimal places separator if the complete scale digits are zero (60.000).

Cast the to_char result to numeric and then to text. This will also remove
trailing zeros.

select
to_char('60.000'::numeric, 'FM999.999')::numeric::text,
to_char('60.100'::numeric, 'FM999.999')::numeric::text;

to_char | to_char
---------+---------
60 | 60.1
(1 row)

> The current behaviour might be intentional but it 'smells like a bug' to me.

It follows Oracle's to_char behavior:

select to_char('60.000', 'FM999.999') from dual;

TO_CHAR('60.000','FM999.999')
-----------------------------
60.

--
Erik

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