MySQL custom function Implementation of recursive hierarchy in the table display

1. Now take the menu table as an example to create a table Test_menu in the database.

2. Create some instance data in the table

Now the menu level for Cd_1 and Cd_2 for a first-level menu, Cd_1 is divided into cd_1_1 and cd_1_2 two level two menu, Cd_1_1 has a three-level menu cd_1_1_1, directory structure as follows

Cd_1

Cd_1_1

Cd_1_1_1

Cd_1_2

Cd_2

3. Create a Custom function

4. Query Menu Hierarchy

Here, the menu is clearly displayed at all levels.

MySQL custom function Implementation of recursive hierarchy in the table display