PHP / Smarty Tricks - Avoid looping for more than one loop for select query

The best way is we can use "IN_ARRAY" method, Here is the basic sample i have given,

{assign var = "exp" value = ","|explode:$catid}
  {section name=k loop=$blogcat}
   <option {if in_array($blogcat[k].CAT_ID, $exp)} selected="selected"  {/if}  value="  {$blogcat[k].CAT_ID}"  >{$blogcat[k].CAT_NAME}
   </option>                                                        
{/section}