Archive for March 17th, 2009
Hierarchical queries in MySQL
This is a series of articles on hierarchical queries in MySQL:
- Hierarchical queries in MySQL
- Hierarchical queries in MySQL: adding level
- Hierarchical queries in MySQL: adding ancestry chains.
- Hierarchical queries in MySQL: finding leaves
- Hierarchical queries in MySQL: finding loops
See also:
There is no need in explaining how convenient hierarchical queries are.
A quick reminder: hierarchical data is a parent-child relationship contained in one table.
A typical task is to return values from the table in the following way:
- Resultset should be sorted like a tree, that is lexical sort by ancestry chains
- Depth level should be returned along with each row
It may sound confusing, but it's very simple in fact, like shown on this Oracle query:
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