Re: [PHP-DB] grabbing from multiple tables

GOLD!
Thank you.

Karl


On May 1, 2010, at 4:12 AM, Peter Lind wrote:

> On 1 May 2010 11:00, Karl DeSaulniers <[email protected]> wrote:
>> Thank you Peter... again.. :)
>> Which would be the source field and which the target field?
>
> You place the constraint on the table that has the foreign key. Using
> your example:
>
> Table 1 = products
> * id = primary key
>
> Table 2 = productoptions
> * product_id = foreign key
>
> On table 2 you would place a constraint like this (in SQL):
> CONSTRAINT FOREIGN KEY (product_id) REFERENCES products (id) ON  
> DELETE CASCADE
>
> This will delete any rows in table 2 if a matching row in table 1 is
> deleted (i.e. if you delete a product, all rows in table 2 matching
> options to products will be deleted as well, if they reference the
> deleted product).
>
> If instead you want to make sure that no product can be deleted while
> it still has options attached, use this:
>
> CONSTRAINT FOREIGN KEY (product_id) REFERENCES products (id) ON  
> DELETE NO ACTION
>
> I don't really know how this translates into your "source" and
> "target" but I would guess source means the primary key on table 1 and
> target means the foreign key on table 2 ... though, thinking about it,
> it would make at least as much sense the other way round. Best see if
> you can find some documentation to translate those terms into
> something SQL-centric
>
> Regards
> Peter
>
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Karl DeSaulniers
Design Drumm
http://designdrumm.com