create database test;
create table users(
id int not null,
name varchar(10),
pwd varchar(10),
email varchar(20)
)
insert into users values(1,'shunping','shunping','aa@163.com');
insert into users values(2,'shunping2','shunping2','bb@163.com');

$active_group = "default";
$db['default']['hostname'] = "localhost";
$db['default']['username'] = "postgres";
$db['default']['password'] = "admin";
$db['default']['database'] = "test";
$db['default']['dbdriver'] = "postgre";
$db['default']['dbprefix'] = "";
$db['default']['active_r'] = TRUE;
$db['default']['pconnect'] = FALSE;
$db['default']['db_debug'] = TRUE;
$db['default']['cache_on'] = FALSE;
$db['default']['cachedir'] = "";
$db['default']['port'] = "5432";

<?php
class Db1 extends Controller{
  function index(){
    $this->load->database();
    $query=$this->db->query("select name,pwd,email from users");
    foreach ($query->result() as $row) {//返回对象数组
      echo $row->name;
      echo $row->pwd;
      echo $row->email."<br>";
    }
    echo "Total Result==".$query->num_rows();
  }
}
?>