how to get count of rows in codeigniter code example

Example 1: row count in codeigniter

$this->db->where('EmpID >=', 5);
$query = $this->db->get('Employees');
echo $query->num_rows();

// Outputs, 4

Example 2: codeigniter count rows

$this->db
  ->where(['field'=>'foo'])
  ->from("tablename")
  ->count_all_results();

//OR 
$this->db
  ->where(['field'=>'foo'])
  ->count_all_results("tablename");