Re: Recursive queries
От | Jeff Eckermann |
---|---|
Тема | Re: Recursive queries |
Дата | |
Msg-id | 02f301c142cd$bd6bebe0$279c10ac@INTERNAL обсуждение исходный текст |
Ответ на | Recursive queries (Juan Jose Comellas <juanjo@comellas.org>) |
Список | pgsql-general |
There was a detailed post by Joe Celko not long ago, which discussed how to handle trees in SQL. I suggest you look at the list archives to find this. ----- Original Message ----- From: "Juan Jose Comellas" <juanjo@comellas.org> To: <pgsql-general@postgresql.org> Sent: Friday, September 21, 2001 11:14 AM Subject: [GENERAL] Recursive queries > I have a database with the following fields: > > product_id INTEGER > parent_id INTEGER > name VARCHAR(64) > > The idea is that it will store a tree of products and its subproducts. Any > row whose parent_id is NULL will be assumed to be a root product (i.e. top > level). > > This means I will need to process recursively, with some sort of reference to > parent_id passing through layers of recursion. > > However, I want to save on database queries and do a "SELECT *", then fetch > each row on the results recursively, to build the tree. The idea is to only > have to do one db query. > > Does anyone have any idea how this can be done in PostgreSQL? Both Oracle and > DB2 support this with their own proprietary syntax. > > > -- > Juan Jose Comellas > (juanjo@comellas.org) > > ---------------------------(end of broadcast)--------------------------- > TIP 2: you can get off all lists at once with the unregister command > (send "unregister YourEmailAddressHere" to majordomo@postgresql.org) > >
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