Getting hierarchy data from a self-referencing table
- by Emanuil
Let's say you have the following table:
items(item_id, item_parent)
... and it is a self-referencing table as item_parent refers to item_id.
What SQL query would you use to SELECT all items in the table along with their depth where the depth of an item is the sum of all parents and grand parents of that item.
If the following is the content of the table:
item_id item_parent
----------- -----------
1 0
2 0
3 2
4 2
5 3
... the query should retrieve the following set of objects:
{"item_id":1,"depth":0}
{"item_id":2,"depth":0}
{"item_id":3,"depth":1}
{"item_id":4,"depth":1}
{"item_id":5,"depth":2}
P.S. I'm looking for a MySQL supported approach.
