Naz writes
>The definitive answer to anything that
>requires trees in SQL is nested sets.
They are not definitive when the tree is large and must be updated
frequently.
PB
-----
Naz Gassiep wrote:
> The definitive answer to anything that requires trees in SQL is nested
> sets. I have written a tutorial on the subject, as this is about the
> most asked question in DB relational data modeling.
>
> http://www.mrnaz.com/static/articles/trees_in_sql_tutorial/
>
> Enjoy :)
>
> - Naz.
>
> Peter Brawley wrote:
>
>> tbt
>>
>>
>>> the number of levels in this table is unknown and the query should work
>>> for any number of levels
>>> please provide a sample 'select' query in mysql
>>>
>> That's a graph, which is recursive, so you need an sproc. See edge
>> list sprocs at
>> http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch20.html.
>>
>> PB
>>
>> -----
>>
>> tbt wrote:
>>
>>>> Hi
>>>>
>>>> i have a table like this
>>>>
>>>> id name parent_id
>>>> 1 europe
>>>> 2 spain 1
>>>> 3 england 1
>>>> 4 france 1
>>>> 5 london 3
>>>> 6 mayfair 5
>>>> 7 madrid 2
>>>>
>>>> in this table each destination is mapped to a parent destination
>>>> eg: mayfair is mapped to london, london is mapped to england etc.
>>>>
>>>> i like to write a query to find child destinations when an id is
>>>> given for
>>>> a parent destination
>>>> eg: if 3 is the id, then the result of query should be 3,5,6
>>>> if 2 is the id, then the result should be 2,7
>>>>
>>>> the number of levels in this table is unknown and the query should work
>>>> for any number of levels
>>>> please provide a sample 'select' query in mysql
>>>>
>>>>
>
>
