Re: Wird behavour of foreign keys

Sorry, I cannot reproduce that behaviour. I guess there are more
triggers or rules in the schema than you are currently aware of.
Especially the deleting from groups is very suspicious.

what does \d for all these tables tell?

Jan

lundeman(at)tbkol(dot)dk wrote:

> Hi list
>
> As I'm new to this list please kick me in the right direction if this question
> is better asked somewhere else.
>
> I'm seing some wird behavoure regarding foreign keys.
>
> My situation is this:
> I have 3 tables:
>
> pages
> PK: page_id
>
> page_group
> pk: page_group_id
> fk: pages(page_id) ON DELETE CASCADE, ON UPDATE NO_ACTION
> fk: groups(group_id) ON DELETE CASCADE, ON UPDATE NO_ACTION
>
> groups
> pk: group_id
>
> let's say I have the following data:
>
> pages: page_group: groups:
> page_id pg_id | page_id | group_id group_id
> 1 1 | 1 | 1 1
> 2 2 | 1 | 2 2
>
> (I know this could be done more easy and the page_group table could be dropped,
> but I did not make the design, I'm just struggling with it)
>
> Now, if I move a group (say with id 1) from one page (page 1) to another (page
> 2)I do it by;
> UPDATE page_group set page_id=2 WHERE page_group_id=1;
>
> Now I have:
>
> pages: page_group: groups:
> page_id pg_id | page_id | group_id group_id
> 1 1 | 2 | 1 1
> 2 2 | 1 | 2 2
>
> Now I have moved group 1 from page 1 to page 2. BUT if I delete page 1 then
> page_group 1 and 2 are both delted, and so are the two groups.
>
> This is not what I would expect, as I have moved group 1 to page 2.
>
> Is this a BUG, or is it something that I'm doing wrong.
> As i understand the ON UPDATE constraint on the foreignkey, it will only update
> the foreign key if the value which it references is changed, which is not what
> I'm doing.
>
> Hope someone can help me, or tell me if it's a bug or not. Because I'm going
> crazy here.
>
> Rene' Jensen
>
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