Re: [GENERAL] Tree structure
От | K.T. |
---|---|
Тема | Re: [GENERAL] Tree structure |
Дата | |
Msg-id | 001001be617d$6c5ea1e0$6adaa5ce@p2-400-death обсуждение исходный текст |
Список | pgsql-general |
Its been a while since I wrote this and its kinda fuzzy at this hour, but this will give you a general direction to go and you can work out the specifics... If you know the depth of the tree then you can create a field of a specified length and store something like: tree_field varchar(16) A AA AB ABA ABB ABC AC This allows you to select all records that are in level "B" fairly easily with a "like" clause. Note that everything has a root of "A". Or you can create two fields: Parent/Child A/B B/E E/G B/F A/C A/D This one is confusing and there is no easy way to show the tree in text. You cannot use the same number for a node. eg. if your first level is "A" then none of your sub levels can be "A". So use the sequence generator to generate a unique key for each node. Then your select would look something like this: Select * from hierachy_table where parent_key = child_key and parent_key = "A"; This should give you all branches under the "A" node. To get the indention...hmmm try ordering the records by parent/child and writing code that loops thru the records? That one stumps me...gotta sleep on it :) DISCLAIMER: This might not be 100% accurate...its a seat of the pants memory. Anyone who knows this please feel free to correct my errors :) -----Original Message----- From: Kaare Rasmussen <kar@webline.dk> To: pgsql-general@postgreSQL.org <pgsql-general@postgreSQL.org> Date: Friday, February 26, 1999 3:02 AM Subject: [GENERAL] Tree structure >I can't figure this one out. I need a tree structure like this > >Number Pointer >1 0 >2 1 >3 1 >4 2 >5 0 >6 1 >7 5 > >This should somehow show up like this >Number >1 >2 >4 >3 >6 >5 >7 > >The whole excercise is because I'd like to show a tree structure: > >1 >- 2 >- - 4 >- 3 >- 6 >5 >- 7 > >Is this possible with PostgreSQL? > >
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