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From:bruce Date:January 16 2012 10:14pm
Subject:Re: Parent/Child - Linked List
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hi Peter.

Sorry.. Been looking at this for awhile.

In the sample data/tbl I provided, it has two top level root/parents.
Ie, I have two entries that don't have a
parentID. I use 0 to be null.

The items are (0,1), and (0,8).

The (0,1) item, has a number of descendants. The (0,8) only has a
single descendant. For my app, I'm going to have a number of top level
items, and they're each going to have a number of descendants, where I
don't know the number of descendant rows, or the number of actual
descendants.

But either way, once I get the descendant list, I still need some way
of linking the childID of the descendant to the linked ID of the
statusTBL so I can get the status of the childID/app.

And like I said, I'm not quite sure how to proceed in an efficient
manner on this.

Thanks



On Mon, Jan 16, 2012 at 4:08 PM, Peter Brawley
<peter.brawley@stripped> wrote:
> On 1/16/2012 2:08 PM, bruce wrote:
>>
>> Hi Peter.
>>
>> Not a mysql guru... so I've never used stored procedures/sub-queries..
>>
>> But it sort of makes sense.
>>
>> What I'm really trying to get is to be able to take a test table like
>> below
>>
>> LOCK TABLES `parentChildTBL` WRITE;
>> /*!40000 ALTER TABLE `parentChildTBL` DISABLE KEYS */;
>> INSERT INTO `parentChildTBL` VALUES
>> (0,1,1),
>> (1,2,2),
>> (1,3,3),
>> (1,4,4),
>> (2,5,5),
>> (2,6,6),
>> (2,7,7),
>> (0,8,8),
>> (8,9,9);
>> UNLOCK TABLES;
>>
>> and to be able to generate the child/descendant list of the top two/2
>> items (1,8)
>
>
> I don't understand "top two(1,8)". In general a non-procedural query of n
> recursion levels requires n-1 joins. If the number of recursive references
> is unknown beforehand, the only way to query the tree is via a stored
> procedure.
>
> PB
>
>
> ----- if I only have a single top level item.. and can do a left join.. but
> I'm not sure how to accomplish this with two top items, unless I take a look
> at the approach you provided. I'm looking at being able to compare a
> 'status' from a linked tbl, that links on the childID... thanks On Mon, Jan
> 16, 2012 at 2:33 PM, Peter Brawley <peter.brawley@stripped> wrote:
>>>
>>> On 1/16/2012 12:53 PM, bruce wrote:
>>>>
>>>> On Mon, Jan 16, 2012 at 1:52 PM, bruce<badouglas@stripped>  
>  wrote:
>>>>>
>>>>> Hey Authur.
>>>>>
>>>>> Should have been more clear. I've looked over a number of sites. And
>>>>> with the exception of the the articles that talk about using the
>>>>> "Nested List" approach, nowhere did I find data on how to get a
>>>>> complete list of the child descendants of a given 'root'/top item
> from
>>>>> the parent/child TBL.
>>>
>>>
>>> Look again, eg listings 7 through 7d in
>>> http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch20.html.
>>>
>>> PB
>>>
>>> -----
>>>
>>>
>>>>> Chunks of code/pointers would be seriously useful.
>>>>>
>>>>> Thanks
>>>>>
>>>>>
>>>>> On Mon, Jan 16, 2012 at 12:18 PM, Arthur
>>>>> Fuller<fuller.artful@stripped>
>>>>>  wrote:
>>>>>>
>>>>>> See the piece on trees at www.artfulsoftware.com. It goes into
> several
>>>>>> variations of how to handle hierarchies.
>>>>>>
>>>>>> HTH,
>>>>>> --
>>>>>> Arthur
>>>>>> Cell: 647.710.1314
>>>>>>
>>>>>> Prediction is difficult, especially of the future.
>>>>>>   -- Neils Bohr
>>>>>>
>>>>>>
>
Thread
Parent/Child - Linked Listbruce16 Jan
  • Re: Parent/Child - Linked ListArthur Fuller16 Jan
Re: Parent/Child - Linked Listbruce16 Jan
  • Re: Parent/Child - Linked ListPeter Brawley16 Jan
Re: Parent/Child - Linked Listbruce16 Jan
  • Re: Parent/Child - Linked ListPeter Brawley17 Jan