For issues relating to arranging items into ordered levels.

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23
votes
3answers
20k views

Find highest level of a hierarchical field: with vs without CTEs

note: this question has been updated to reflect that we are currently using MySQL, having done so, I would like to see a how much easier it would be if we switched to a CTE-supporting database. I ...
15
votes
3answers
3k 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 ...
9
votes
6answers
2k views

Tables with hierarchy: create a constraint to prevent circularity through foreign keys

Suppose we have a table that has a foreign key constraint to itself, like such: CREATE TABLE Foo (FooId BIGINT PRIMARY KEY, ParentFooId BIGINT, FOREIGN KEY([ParentFooId]) REFERENCES ...
12
votes
3answers
2k views

Anybody using HierarchyId in production? Is it reliable?

Is anybody using HierarchyId in real production with tables of reasonable size, more than a few thousand rows? Is it reliable/performant? So far I have not found anyone not affiliated with the vendor ...
4
votes
1answer
289 views

Hierarchical queries without CTEs

I'm new to MySQL. The GetFamilyTree(id) function that Rolando suggested in the Find highest level of a hierarchical field: with vs without CTEs question was great but when the id is greater than 999 ...
1
vote
1answer
2k views

Get top most parent by nth child id?

Now there is a question we commonly use this technique to maintain the parent child relation i.e we store all the entities in one tables with a parent_id column and all top most parents have 0 in the ...