“self-referencing” table and arrays

Question

MySQL table:

categoryID  
categoryName  
categoryParent

Every category has ONE parent category, though it can be NULL, which I treat as the root-category.

I want to get all categories from the table, store it in an array and print it in a way, that shows the nesting.

Example:

ID  name    parent  
1   a       NULL  
2   b       NULL  
3   c       NULL  
4   b1      2  
5   d       NULL  
6   b2      2 

HTML:

a  
b  
-b1  
-b2  
c  
d  

Later I'll try to make it draggable with jQuery so the user can choose the parent/child category by him-/herself.

Can I do all this with one single table or do I need an external junction table?

Answer 1

Your table structure is fine.

You'll render the nesting when you deal with the results; perhaps you loop through each result with no parent and append to the DOM, then loop through each result with a parent appending to existing elements. That only works for a two-level tree, but you get the idea.

Answer 2

Yes you can, just select all the rows from table. And using php, you can generate a good html table using a for loop. When you see an element with a parent, just process the table string you are constructing in your php script. From there using JQuery you can change the orders and parent child relationship of the table.

Answer 3

You can nest arrays and have a structure like (Array of (me, childrenArray)). That way you use the "me" for indexing.