pdo = $pdo; $this->table = $table; $this->key = $key; } public function execute(array $data) { if (! $this->isFieldNotEmpty($data)) { return true; } if ($this->key === '') { $this->key = $this->field; } $rq = $this->pdo->prepare('SELECT 1 FROM '.$this->table.' WHERE '.$this->key.'=?'); $rq->execute(array($data[$this->field])); return $rq->fetchColumn() == 1; } }