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Posted by Jerry Stuckle on 06/25/06 03:14
IchBin wrote:
> Geoff Berrow wrote:
>
>> Message-ID: <1151197943.581310.88860@b68g2000cwa.googlegroups.com> from
>> frizzle contained the following:
>>
>>> I'm building a music site with a mysql backend. It has a many to many
>>> relational database.
>>> I use this to match music genres with certain artists, to maintain the
>>> possibility to add multiple genres to a singe artist.
>>>
>>> Now i've searched google, but can't find a solution on how to update
>>> rows with checkboxes.
>>> If an artist gets his genre updated as follows:
>>> from
>>>
>>> - [_] classic
>>> - [X] rock
>>> - [_] ballad
>>> - [X] 80's
>>> - [_] 90's
>>> - etc.
>>>
>>> to
>>>
>>> - [_] classic
>>> - [_] rock
>>> - [_] ballad
>>> - [_] 80's
>>> - [X] 90's
>>> etc.
>>>
>>> wha t i wonder is how could i best create the backend. it would seem
>>> inappropraite to run an update query for each possible box wether it's
>>> checked or not.
>>
>>
>> It depends how you have structured your db. For a many to many
>> relationship like this you ideally need three tables, one for artists,
>> one for genres and one to link the two.
>>
>> In the case above you would start with two rows in the link table.
>> Updating would require removing a row, though it may be simpler to
>> remove them all and then write a new one.
>>
>>
>>
>
> I do not think you need three tables. Genres is an adjective describing
> either a song or the singer singer. A Genre should be added to both
> tables because each singer could have more that one Genre but one song
> can only be one Genre. But then again one song can have multiple singers.
>
>
> Thanks in Advance...
> IchBin, Pocono Lake, Pa, USA http://weconsultants.awardspace.com
> __________________________________________________________________________
>
> 'If there is one, Knowledge is the "Fountain of Youth"'
> -William E. Taylor, Regular Guy (1952-)
I'd suggest you read up on "database normalization" and how it prevents the
problems which can be caused by your method.
Also, a song may have multiple genre's. For instance - it could be "Rock" and
"80's". Or, depending on how it was played/sung, it could be "Country" or "Rock".
--
==================
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Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
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