是否可以在单个查询中查询 MySQL 中的树结构表,任何深度?

我认为答案是否定的,但我希望任何人都可以深入了解如何在 SQL (MySQL) 中将树结构爬到任何深度,但只需要一个查询

I'm thinking the answer is no, but I'd love it it anybody had any insight into how to crawl a tree structure to any depth in SQL (MySQL), but with a single query

更具体地说,给定一个树结构的表(id、data、data、parent_id),以及表中的一行,是否可以得到所有后代(child/grandchild/etc),或者就此而言,所有祖先(父母/祖父母/等)不知道它会下降多远,使用单个查询?

More specifically, given a tree structured table (id, data, data, parent_id), and one row in the table, is it possible to get all descendants (child/grandchild/etc), or for that matter all ancestors (parent/grandparent/etc) without knowing how far down or up it will go, using a single query?

或者正在使用某种递归要求,在那里我不断查询更深入,直到没有新结果?

Or is using some kind of recursion require, where I keep querying deeper until there are no new results?

具体来说,我使用的是 Ruby 和 Rails,但我猜这不是很相关.

Specifically, I'm using Ruby and Rails, but I'm guessing that's not very relevant.

推荐答案

是的,这是可能的,它被称为 Modified Preorder Tree Traversal,如此处所述

Yes, this is possible, it's a called a Modified Preorder Tree Traversal, as best described here

Joe Celko 在 SQL for Smarties 中的树和层次结构

此处提供了一个工作示例(在 PHP 中)

A working example (in PHP) is provided here

http://www.sitepoint.com/article/hierarchical-data-database/2/

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