Php Crud Abstraction Layer using array

Crud.php

<?php
/**
 * Crud class 
 * 
 * LICENSE FREE TO USE WITHOUT ANY WARRANTY
 * How to use:
 * Create class name extends Crud or change private method to public.
 *  
 */

class Crud {

        private $result = array();

        /*
        *   set to your database name, etc
        *
        */        
        public function __construct() {
        }


        /*
        *   return $this->insert('table', array('column1' => $_POST['field'])); 
        *
        */
	protected function insert($table, $data) {
	
		$insert = sprintf('INSERT INTO %s (%s) VALUES ("%s")', $table, 
		          implode(', ', array_map('mysql_escape_string', array_keys($data))), 
		          implode('", "',array_map('mysql_escape_string', $data)));
		
		    if(mysql_query($insert)) {
		    	return true;
		    } else {
			    return false;
		    }			
	}


        /*
        *    $this->select('table', array('id', 'username',), array('id' =>   $id)); 
        *   return $this->getResult();
        *   select id, username from table where id=$id
        */
    protected function select($table, $column = NULL, $data=NULL) {
        if(!empty($data)) {
			$query = "SELECT ".implode(', ', $column)." FROM `$table`"  . $this->where_list($data);
		    
		} else {
			$query = "SELECT * FROM `$table`"   . $this->where_list($data);	
		}
		$query = mysql_query($query);
		
        if($query) {
            $this->numResults = mysql_num_rows($query);
            for($i = 0; $i < $this->numResults; $i++) {
                $r = mysql_fetch_array($query);
                $key = array_keys($r);
                for($x = 0; $x < count($key); $x++) {
                    // Sanitizes keys so only alphavalues are allowed
                    if(!is_int($key[$x])) {
                        if(mysql_num_rows($query) > 0)
                            $this->result[$i][$key[$x]] = htmlentities($r[$key[$x]]);
                        else if(mysql_num_rows($query) < 1)
                            $this->result = null;
                        else
                            $this->result[$key[$x]] = htmlentities($r[$key[$x]]);
                    }
                }
            }
            return true;
        }
        else
        {
            return false;
        }
	}

    /*
    * Returns the result set
    */
    protected function getResult() {
        return $this->result;
    }


    protected function doCount($table, $data = array()) {
		$query = mysql_query("SELECT COUNT(id) FROM `$table`" . $this->where_list($data));
        list($row) = mysql_fetch_row($query);
        return $row;
	}
	
	protected function doUpdate($table, $data = array(), $where = array()) {
		foreach($data as $key => $value) { 
			$query = "UPDATE $table SET ". $this->column_list($data) . $this->where_list($where);
			return mysql_query($query);
		}
		
	}
	
	private function column_list($conditions = array()) {
        $output = " SET ";
		foreach((array) $conditions as $column => $value) {
			//If the value is an aray it must be an IN clause
			if(is_array($value)) {
				$output .= "`".$column."`". "'$value'";
			} else {
				$output .= "`".$column."`". " = "
				. ($value == '?' ? $value : "'$value'"). ", ";
			}
		}
		
		return rtrim($output, ", ");
	}
	
	private function where_list($conditions = array()) {
		$output = " WHERE ";
		foreach($conditions as $column => $value) {
			//If the value is an aray it must be an IN clause
			if(is_array($value)) {
				$output .= $column. "'$value'";
			} else {
				$output .= $column. " = "
				. ($value == '?' ? $value : "'$value'"). " AND ";
			}
		}
		return rtrim($output, " AND ");
	}

}