How could I list Category And Subcategory under it Select with PHP with unlimited subcategory like Cat3 under Cat2, Cat2 under Cat1

Örneğin ben istiyorum:

Parent
- Category1
- Category2
-- SubCategory1
-- SubCategory2
- Category3
-- SubCategory1

This is a simple example for what I need, so I want to make unlimited subcategories. Like Nested set...