php: Tree structure algorithm_PHP tutorial

We will encounter such problems in product classification, multi-level tree-structured forums, mailing lists and many other places: How to store multi-level structured data?

In PHP applications, the backend data storage is usually a relational database, which can save large amounts of data and provide efficient data retrieval and update services. However, the basic form of relational data is a criss-crossed table, which is a flat structure. If you want to store a multi-level tree structure in a relational database, you need to perform reasonable translation work. Next, I will discuss with you what I have seen and heard and some practical experiences.

There are basically two common design methods for storing hierarchical data in flat databases:

Adjacency list model (adjacency list model)

Pre-sorted tree traversal algorithm (modified preorder tree traversal algorithm)

I am not a computer major, and I have never learned anything about data structures, so I translated these two names according to their literal meanings. If I am wrong, please let me know. Please give me some advice.

These two things may sound scary, but they are actually very easy to understand. Here I use a simple food directory as our example data. Our data structure is like this:

Food

|

|---Fruit

| |

| |- --Red

| | |

| | |--Cherry

| |

| |---Yellow

| >

|

|--Pork

To take care of those PHP enthusiasts whose English is a mess

Food: food

Fruit: fruit

Red: Red

Cherry: Cherry

Yellow: Yellow

Banana: Banana

Meat: Meat

Beef: Beef

Pork: Pork

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We will encounter such problems in product classification, multi-level tree-structured forums, mailing lists and many other places. : How to store multi-level structured data? In PHP applications, provide background data...