Questions tagged [tree]

Trees are special cases of graphs. They are acyclic i.e. there is at most one path from any node to any other node. Typical uses include hierarchical data (parent-child relationships; roll-up aggregate values) and BTree indexes.

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1answer
13k views

Recursive Query in MySQL using stored proceedure and CURSOR

I'm expanding our user/group system to allow for dynamic groups which are made up of other groups members. I have three tables users, groups, and relationships. For simplicity sake, lets say users ...
16
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4answers
8k views

Traversing tree-like data in a relational database using SQL

Is there a way to traverse tree data in SQL? I know about connect by in Oracle, but is there another way to do this in other SQL implementations? I'm asking because using connect by is easier than ...
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2answers
6k views

Best design for a tree-like structure database

I'm designing a database in MS Access which is used for tracking the locations of a variety of chemical solutions, made in batches. Each batch can be split (aliquoted) practically indefinitely. That ...
10
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3answers
24k views

COUNT of rows with parent id equal to the row we have with a parent id of 0 in one query

I'd like to do the following in one query using MySQL: grab a row that has a parent_id of 0 grab a count of all the rows that have a parent_id of the row that we grabbed which has a parent_id of 0 ...
1
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1answer
1k views

Implement a Parent-Level Count in Binary Search Tree

Based on this question, have any way to implement a parent level count? Find highest level of a hierarchical field: with vs without CTEs Example table: +----+-----------+ | id | parent_id | +----+-...
2
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0answers
21 views

Drop intermediate results of recursive query in Postgres

I'm trying to aggregate the contents of a column from a directed acyclic graph (DAG) stored in a Postgres table. Each dag row has an id, bytes, and may also have a parent referencing another row. I'm ...
1
vote
1answer
28 views

Recursively find the path to all leaves descending from a given parent in a tree

I'm trying to write a query to identify the path to each furthest descendant of a particular parent node in a table of tree structures like: 0 1 | | 2 3 | | 4 5 ...