title: Change the array KEY to a value from sub array
body: <p>This is the set of result from my database</p>
  
  <pre><code>print_r($plan);
  Array
  (
      [0] =&gt; Array
          (
              [id] =&gt; 2
              [subscr_unit] =&gt; D
              [subscr_period] =&gt; 
              [subscr_fee] =&gt; 
          )
  
      [1] =&gt; Array
          (
              [id] =&gt; 3
              [subscr_unit] =&gt; M,Y
              [subscr_period] =&gt; 1,1
              [subscr_fee] =&gt; 90,1000
          )
  
      [2] =&gt; Array
          (
              [id] =&gt; 32
              [subscr_unit] =&gt; M,Y
              [subscr_period] =&gt; 1,1
              [subscr_fee] =&gt; 150,1500
          )
  
  )
  </code></pre>
  
  <p>How can I change the <code>$plan[0]</code> to <code>$plan[value_of_id]</code></p>
  
  <p>Thank You.</p>