Re: Difficulty modelling sales taxes

On 01/02/2017 06:38 AM, Melvin Davidson wrote:
>
> On Mon, Jan 2, 2017 at 6:29 AM, Frank Millman <frank@chagford.com
> <mailto:frank@chagford.com>> wrote:
>
>
>     *From:* amul sul
>     *Sent:* Monday, January 02, 2017 12:42 PM
>     *To:* Frank Millman
>     *Cc:* pgsql-general
>     *Subject:* Re: [GENERAL] Difficulty modelling sales taxes
>
>     > On Mon, Jan 2, 2017 at 4:03 PM, Frank Millman <frank@chagford.com
>     <mailto:frank@chagford.com>> wrote:
>     >
>     > Hi all
>     >
>     >
>     >
>     > It is a bit ugly, because I have to use the ‘NVARCHAR code’ column from
>     >
>     > tax_codes, not the primary key, but I think it would work.
>     >
>     >
>     >
>     NVARCHAR ?  Are you using PostgreSQL as database server?
>     >
>
>
>     Oops, sorry.
>
>     I am testing with PostgreSQL and with SQL Server, so I was in the
>     wrong mindset when I posted.
>
>     I should have said VARCHAR.
>
>     Frank
>
>
>
>
>
> *First, there is no need to make row_id's when you already have a valid
> primary key.

In a perfect world yes, but this is a world with ORM's as I found out 
the hard way:

https://docs.djangoproject.com/en/1.10/ref/models/fields/#primary-key

"The primary key field is read-only. If you change the value of the 
primary key on an existing object and then save it, a new object will be 
created alongside the old one."



-- 
Adrian Klaver
adrian.klaver@aklaver.com