通过从数据库mysql中获取数据，在php中创建一个多级别类别

Question

I have database table that has these values:

ID  and  SUB  
--       --

1         0
2         0
3         0
4         0
5         0 

Now from php/mysql I'm trying to do this: if I put for example the value of ID to SUB, to create a <ul><li></li><ul> level. For example: if ID=5 has SUB=1, then I should have

<ul>
  <li> 1
    <ul><li> 5 </li></ul>
  </li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
</ul>

If, for example, ID=1 has SUB=2, then I should have:

<ul>
  <li> 2
    <ul><li> 1 
      <ul><li>5</ul>
  </li></ul>
  <li>3</li>
  <li>4</li>
</ul>

</div>