Re: Alter table column constraint
От
Ron
Тема
Re: Alter table column constraint
Дата
Msg-id
d0845332-78ec-5387-6672-aaf50e0b5968@gmail.com
Ответ на
Re: Alter table column constraint (Rich Shepard)
Список
Дерево обсуждения
Alter table column constraint Rich Shepard <rshepard@appl-ecosys.com>
Re: Alter table column constraint Rich Shepard <rshepard@appl-ecosys.com>
Re: Alter table column constraint "Joshua D. Drake" <jd@commandprompt.com>
Re: Alter table column constraint Melvin Davidson <melvin6925@gmail.com>
Re: Alter table column constraint Rich Shepard <rshepard@appl-ecosys.com>
Re: Alter table column constraint Adrian Klaver <adrian.klaver@aklaver.com>
Re: Alter table column constraint "David G. Johnston" <david.g.johnston@gmail.com>
Re: Alter table column constraint Melvin Davidson <melvin6925@gmail.com>
Re: Alter table column constraint Melvin Davidson <melvin6925@gmail.com>
Re: Alter table column constraint Ron <ronljohnsonjr@gmail.com>
Re: Alter table column constraint [RESOLVED] Rich Shepard <rshepard@appl-ecosys.com>
On 12/17/2018 02:20 PM, Rich Shepard wrote:
> On Mon, 17 Dec 2018, Melvin Davidson wrote:
>
>> Yes, you must drop then add the revised constraint. However, from your
>> statement above, it sounds to me as if you would be better off using A
>> FOREIGN kEY CONSTRAINT. It makes things a lot simpler.
>
> Melvin,
>
> I don't follow. Here's the DDL for that column:
>
> industry varchar(24) NOT NULL
> CONSTRAINT invalid_industry
> CHECK (industry in ('Agriculture', 'Business, other', 'Chemicals',
> 'Energy', 'Law', 'Manufacturing', 'Mining', 'Municipalities',
> 'Ports/Marine Services', 'Transportation')),
>
> and I want to remove Municipalities for the more general Government.
Melvin is saying to:
1. create a table named valid_industry,
2. populate it with the valid industries,
3. create an FK constraint on your main table's industry column to
valid_industry.industry, and then
4. drop the constraint invalid_industry.
--
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