Call to undefined method CI_DB_mysql_driver::num_rows()

问题

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Welcome_model extends CI_Model {

      public function select(){

                  $this->db->get('av_home');
                  echo $this->db->num_rows();

      }
}

Above code gives error,

Call to undefined method CI_DB_mysql_driver::num_rows()

回答1:

The number of rows returned by the query.With num_rows() you first perform the query, and then you can check how many rows you got.

$query is the variable that the query result object is assigned to:

 $query=$this->db->get('av_home');// assign to a variable
 echo $query->num_rows();// then use num rows

回答2:

class Welcome_model extends CI_Model {

      public function select(){

            echo $this->db->get('av_home')->num_rows();

      }
}

来源：https://stackoverflow.com/questions/31625729/call-to-undefined-method-ci-db-mysql-drivernum-rows