Re: Constraint + where

On Sun, Mar 19, 2017 at 8:53 PM, Patrick B <patrickbakerbr(at)gmail(dot)com> wrote:

>
>
> 2017-03-20 13:27 GMT+13:00 Melvin Davidson <melvin6925(at)gmail(dot)com>:
>
>>
>>
>> On Sun, Mar 19, 2017 at 8:16 PM, Patrick B <patrickbakerbr(at)gmail(dot)com>
>> wrote:
>>
>>> Hi guys,
>>>
>>> I've got a column 'type_note' on a new table that it's being designed:
>>>
>>> type_note varchar(32) NOT NULL;
>>>
>>> On that column, there will be three different data:
>>>
>>> 1. yes
>>> 2. no
>>> 3. maybe
>>>
>>> I wanna create a FK but just when the data on that column is = maybe.
>>>
>>> How can I do that? Thanks!
>>>
>>>
>> Why just "maybe"? Since there can only be three valid answers, why not FK
>> for all three?
>>
>> --
>>
>
>
>
> I was able to get what I needed this way:
>
> create table testing_fk_conditional_1 (
>> id serial NOT NULL PRIMARY KEY,
>> account_id bigint,
>> user_id bigint,
>> type_note integer NOT NULL,
>> CHECK (type_note = 100 AND user_id IS NOT NULL OR type_note = 200 AND
>> account_id IS NOT NULL)
>> );
>
>
That is not what you asked for originally, but as long as you are happy.

--
*Melvin Davidson*
I reserve the right to fantasize. Whether or not you
wish to share my fantasy is entirely up to you.