PHP SQLQuery Class

SQLQuery.php

<?php

 // Run a query and return results
 class SQLQuery {
   
   public $query = "";
   private $allowed_query_types = array(
       'INSERT'
     , 'DELETE'
     , 'UPDATE'
     , 'SELECT'
   );
   
   // To let us run without instantiating; eg: $results = SQLQuery::query($query);
   public function query($query) {
     $result = new SQLQuery($query);
     return $result->results;
   }
   
   public function __construct($query) {
  
    $this->query = trim($query);
    
    // Get the type of query (insert, delete, update, select) so we know how to handle results
    $query_type = $this->get_query_type();
    
    // Check to make suer its an 'allowed' query type
    if(in_array($query_type, $this->allowed_query_types)) {
      
      $this->execute_query();
      
      // Dynamically runs the method we got before to handle results appropriatly
      $this->$query_type();
    } else {
      $this->results = FALSE;
    } 
   }

   public function get_query_type() {
     // We're just checking the first word of the query to get the query type
     $query_parts = explode(" ", $this->query);
     $query_type = strtoupper($query_parts[0]);
     return $query_type;
   }
   
   public function execute_query() {
     // Run query
     $this->query_results = mysql_query($this->query);
   }
   
   public function insert() {
     // If the query was succesfull return the insert ID, if not return false
     if($this->query_results) {
       $this->results = mysql_insert_id();
     } else {
       $this->results = FALSE;
     }
   }
   
   public function select() {
     $return_array = array();
     
     if($this->query_results) {

       // If there's no results return an emty array
       if(mysql_num_rows($this->query_results) == 0) {
         $this->results = array();

      // If there's only one result return it directly
       } else if (mysql_num_rows($this->query_results) == 1) {
         $this->results = mysql_fetch_assoc($this->query_results);

       // Or if there's many results return an array of them all
       } else {
         while ($row = mysql_fetch_assoc($this->query_results)) {
           $return_array[] = $row;
         }
         $this->results = $return_array;
       }
     } else {
       $this->results = array();
     }
   }
   
   public function delete() {
     // Return results directly, will be TRUE | FALSE
     $this->results = $this->query_results;
   }
   
   public function update() {
      // Return results directly, will be TRUE | FALSE
     $this->results = $this->query_results;
   }
   
 }

?>