Re: Storing multiple items in one MySQL field?

On Jan 10, 2012, at 9:30 AM, B. Aerts wrote:

> On 08/01/12 23:35, Karl DeSaulniers wrote:
>>
>> On Jan 8, 2012, at 10:36 AM, Bastien wrote:
>>
>>>
>>>
>>> On 2012-01-08, at 7:27 AM, Niel Archer <[email protected]> wrote:
>>>
>>>>
>>>> --
>>>> Niel Archer
>>>> niel.archer (at) blueyonder.co.uk
>>>>> Hello phpers and sqlheads,
>>>>> If you have a moment, I have a question.
>>>>>
>>>>> INTRO:
>>>>> I am trying to set up categories for a web site.
>>>>> Each item can belong to more than one category.
>>>>>
>>>>> IE: Mens, T-Shirts, Long Sleeve Shirts, etc.. etc..
>>>>> (Sorry no fancy box drawing)
>>>>>
>>>>> QUESTION:
>>>>> My question is what would the best way be to store this in one  
>>>>> MySQL
>>>>> field and how would I read and write with PHP to that field?
>>>>> I have thought of enum() but not on the forefront of what that
>>>>> actually does and what it is best used for.
>>>>> I just know its a type of field that can have multiple items in  
>>>>> it.
>>>>> Not sure if its what I need.
>>>>>
>>>>> REASON:
>>>>> I just want to be able to query the database with multiple  
>>>>> category
>>>>> ID's and it check this field and report back if that category is
>>>>> present or if there are multiple present.
>>>>> Maybe return as a list or an array? I would like to stay away from
>>>>> creating multiple fields in my table for this.
>>>>
>>>> Have you considered separate tables? Store the categories in one  
>>>> table
>>>> and use a third to store the item and category combination, one  
>>>> row per
>>>> item,category combo. This is a common pattern to manage such  
>>>> situations.
>>>>
>>>>> NOTE:
>>>>> The categories are retrieved as a number FYI.
>>>>>
>>>>> Any help/code would be greatly appreciated.
>>>>> But a link does just fine for me.
>>>>>
>>>>> Best Regards,
>>>>>
>>>>> Karl DeSaulniers
>>>>> Design Drumm
>>>>> http://designdrumm.com
>>>>>
>>>>> Hope your all enjoying your 2012!
>>>>
>>>>
>>>> --
>>>> PHP Database Mailing List (http://www.php.net/)
>>>> To unsubscribe, visit: http://www.php.net/unsub.php
>>>>
>>>
>>> Neil's solution is the best. Storing a comma separated list will
>>> involve using a LIKE search to find your categories. This will  
>>> result
>>> in a full table scan and will be slow when your tables get bigger.
>>> Storing them in a join table as Neil suggested removes the need  
>>> for a
>>> like search an will be faster
>>>
>>> Bastien
>>> --
>>> PHP Database Mailing List (http://www.php.net/)
>>> To unsubscribe, visit: http://www.php.net/unsub.php
>>>
>>
>> Thanks guys for the responses. So.. what your saying if I understand
>> correctly.
>> Have the categories in one table all in separate fields.
>> Than have a the products table. Than have a third table that stores  
>> say
>> a product id
>> and all the individual categories for that product in that table as
>> separate fields associated with that product id?
>>
>> Am I close? Sounds like a good situation, but I didn't want to really
>> create a new table.
>> One product will probably have no more than 3 combinations of
>> categories. So not sure it this is necessary.
>>
>> EG:
>>
>> Tshirts = 1
>> Jackets = 2
>> etc..
>>
>> Mens = 12
>> Womens = 13
>>
>> So lets say I want to find all the Mens Tshirts.. I was wanting one
>> field to hold the 1, 12
>>
>> hope that clarifies
>>
>> Karl DeSaulniers
>> Design Drumm
>> http://designdrumm.com
>>
>
> Hi Karl,
>
> if you don't want to do with the third-table-solution, how about an  
> assembler-style bit-wise OR of all categories ?
>
> constant TSHIRTS = 1 ;  // 2 to the 0th power
> constant JACKETS = 2 ;  // 2 to the 1st power
> constant MENS    = 8 ;  // 2 to the 3rd power
> constant WOMENS  = 16 ; // 2 to the girl power :-)
>
> INSERT INTO TABLE t_myTable ( ID, categoryField)
> VALUES ( myNewId, TSHIRTS | MENS ) ;
>
> SELECT ID
> FROM t_myTable
> WHERE  ( categoryField && ( TSHIRTS | MENS )) > 0 ;
>
> This assumes that your number of categories is not that big of  
> course, as you're limited to 64 bits/categories on a modern machine.
>
> Bert
>
> -- 
> PHP Database Mailing List (http://www.php.net/)
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>

Hi Bert,
Thanks for the response. I did consider that, but there may be more  
than 64 categories.
So I am thinking that may not be best for my situation. I am actually  
at the same point again, but
this time with the colors. I have multiple colors for each tshirt.
I dont want to put all the separate colors as their own fields and  
there is an image associated with those colors too.
I'd also like to not put those all in separate fields if I can.

What's the best way to store multiple values that may change from time  
to time?
What kind of field?

IE:
('red.png', 'green.png', 'blue.png')

SET()
enum()
blob()
varchar()

???
TIA

Karl DeSaulniers
Design Drumm
http://designdrumm.com


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