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Asked: 2026-05-16T15:27:35+00:00

I have a table (this cannot be changed) like the following: POST_ID | PARENT_ID

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I have a table (this cannot be changed) like the following:

POST_ID | PARENT_ID | POST_NAME

1       | 0         | Services
4       | 1         | Development
5       | 4         | Magento
2       | 0         | Contact

The field, ‘parent_id’ references post_id to form a self-referential foreign key. Is it possible to write a single query to connect a post and it’s parents based on the post_id?

For example, if I had the post_id 5 (Magento), could I write a query to produce the following results:

5 | Magento
4 | Development
1 | Services

I know this is quite easy to do with multiple queries, however, wish to know whether it is possible with a single query.

Thanks 🙂

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1 Answer

  1. Editorial Team

    You are organizing your hierarchical data using the adjacency list model. The fact that such recursive operations are difficult is in fact one major drawback of this model.

    Some DBMSes, such as SQL Server 2005, Postgres 8.4 and Oracle 11g, support recursive queries using common table expressions with the WITH keyword (also see @Quassnoi’s comment below). This feature allows queries such as this to be written with ease, but as @OMG Ponies mentioned in a comment above, MySQL does not support recursive queries yet.

    You mentioned that you cannot make any changes to your table, but can you add an additional table? If yes, you may may be interested in checking out the following article which describes an alternative model (the nested set model), which makes recursive operations easier (possible):

    In addition, I also suggest checking out the following presentation by @Bill Karwin, a regular contributor on Stack Overflow:

    The closure table model described in the presentation is a very valid alternative to the nested set. He further describes this model in his SQL Antipatterns book (excerpt from the chapter on this topic [PDF]).

    Otherwise, you may want to do the recursive part in your application, downloading all the data, building a tree, and walking through it.

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