Bluz\Db\Db::fetchColumn PHP Method

    public function fetchColumn($sql, $params = [])
    {
        $stmt = $this->prepare($sql, $params);
        $result = $stmt->fetchAll(\PDO::FETCH_COLUMN);
        $this->ok();
        return $result;
    }

 /**
  * fetchColumn
  */
 public function testFetchColumn()
 {
     $result = $this->db->fetchColumn("SELECT id FROM test LIMIT 10");
     $this->assertEquals(10, sizeof($result));
 }