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
