在codeigniter中,我需要以这样的方式使用count

Question

我需要调用一个查询并获取一些出现的数字.换句话说,我需要一个CodeIgnıter方法,以便查询产生类似于:

SELECT COUNT( * ) AS total FROM comments WHERE `level`= 4

Answer 1

$this->db->select('count(*)');
$this->db->from('comments');
$this->db->where('level','4');
$query = $this->db->get();
echo $query->num_rows();

Answer 2

    $this->db->select('count(*) as total');  
    $this->db->from('comments');
    $this->db->where('level', 4);
    $sql   = $this->db->return_query();
    /*debug*/ 
    /*echo 'sql:: '.$sql;*/
    $query = $this->db->get(); 
    $arr   = $query->row_array(); 
    $total = $arr['total'];