Tree-like data relationships are common, but working with trees in SQL usually requires awkward recursive queries. This talk describes alternative solutions in SQL, including: - Adjacency List - Path Enumeration - Nested Sets - Closure Table Code examples will show using these designs in PHP, and offer guidelines for choosing one design over another.Read less
![Models for hierarchical data](https://cdn-ak-scissors.b.st-hatena.com/image/square/38ddacaf2a042485615907547f5cbc93a0ac0878/height=288;version=1;width=512/https%3A%2F%2Fcdn.slidesharecdn.com%2Fss_thumbnails%2Fmodelsforhierarchicaldata-100520123959-phpapp02-thumbnail.jpg%3Fwidth%3D640%26height%3D640%26fit%3Dbounds)