// Schema 1
	$Schema1 = new Schema1();
	$Schema1_result = $Schema1->select()->from('my_table')->where('age > 18')->result();
	
	// Schema 2
	$Schema2 = new Schema2();
	$Schema2->type = 'SELECT';
	$Schema2->source = 'my_table';
	$Schema2->condition = 'age > 18';
	
	// Schema 3
	$result = Schema3::getInstance()->select($from = 'my_table', $condition= 'age > 18');
	
	// Schema 4
	$result = Schema4::getInstance()->select($from = 'my_table', $condition= 'age > 18');

	class Schema1 {
		
		protected $type = null;
		protected $source = null;
		protected $condition = null;
		
		public function select() {
			$this->type = 'select';
			return $this;
		}
		
		public function from($from) {
			$this->source = $from;
			return $this;
		}
		
		public function where($condition) {
			$this->condition = $condition;
			return $this;
		}
		
		public function result() {
			// Построение запроса
			return mysql_query($query);
		}
	}
	
	class Schema2 {
		
		public $type = null;
		public $source = null;
		public $condition = null;
		
		public function execute() {
			
			if(method_exists($this, $this->type)) {
				$method = $this->type;
				return $this->$method();
			}
		}
		public function select() {
			// Построение запроса
			return mysql_query($query);
		}
	}
	
	class Schema3 {
		
		public function select() {
			$query = self::queryBuilder('SELECT', func_get_args());
		}
		
		
		public function create() {
			$query = self::queryBuilder('INSERT', func_get_args());
		}
		
		public function update() {
			$query = self::queryBuilder('UPDATE', func_get_args());
		}
		
		public function delete() {
			$query = self::queryBuilder('DELETE', func_get_args());
		}
		
		protected static function queryBuilder($action, $from) {
			// Построение запроса
		}
	}
	
	class Schema4 {
		
		protected static function queryBuilder($action, $from) {
			// Построение запроса
		}
		
		public function __call($method, $args) {
			
			$query = self::queryBuilder(strtoupper($method), $args);
			$result = self::execute($query);
			
			if(!is_resource($result)) {
				return self::wrapData($result);
			}
			
			return $result;
		}
	}