Hey there again,
I suggest you look up a tutorial about database normalisation. Good ones
are often hard to find.
In general, you give all tables that contain data you will be
referencing in other tables a numeric id (INT(11) UNSIGNED) as primary
key, and you use that key as the constraint.
Your table `locations` will be referenced in your table `tags` as such:
FOREIGN KEY (`location`) REFERENCES `locations`(`id`) ON UPDATE CASCADE
ON DELETE SET NULL
Search the mysql manual for those update/delete options to see what they
do and adjust them to your needs. The ones given are the ones I in most
situations.
HTH,
boro
Hiep Nguyen schreef:
> Now, if I have a location table with id, name, address, phone, fax, etc...
>
> Should I put id or name into the tag table?
>
> If id used, then how do i look up the name, address, phone, fax, etc... when
> I do a select on tag table?
>
> Thank you for all your helps
> T. Hiep
> -----Original Message-----
> From: Mogens Melander [mailto:mogens@stripped]
> Sent: Monday, July 02, 2007 3:45 PM
> To: mysql@stripped
> Subject: Re: database structure
>
>
> On Mon, July 2, 2007 21:10, Hiep Nguyen wrote:
>
>> take your advice, i looked in to JOIN and i got the idea. but i noticed
>> that in order to use JOIN, don't you need to have the same column name in
>> both tables? i just don't see it in your example here. is there
>> something that i'm missing?
>>
>
> Using the form:
>
> select t1.field1 data1, t2.field1 data2, t3.fieldn data3
> from table_a t1
> left join table_b t2 on ( t1.id=t2.t1_ref )
> left join table_n t3 on ( t2.id=t3.t2_ref );
>
> You can join on allmost anything.
>
> ?? Can typecasts be used in this scenario ??
>
>
>> can u give a select example with JOIN on three tables above?
>>
>
>
