Mysql MAMP堆栈上运行的CodeIgniter中没有选择数据库错误

我在一个常规的MAMP堆栈上安装了ci，我正在处理。但是，我只浏览了Created部分，目前我得到一个No database selected错误

型号：

<?php 
class submit_model extends Model {

    function submitForm($school, $district) {
        $data = array(
            'school' => $school,
            'district' => $district
        );

        $this->db->insert('your_stats', $data);
    }

} 

config.php

$config['base_url']    = "http://localhost:8888/ci/";
...
$config['index_page'] = "index.php";
...
$config['uri_protocol']    = "AUTO"; 

那么，它怎么会给我这个错误信息呢

A Database Error Occurred
Error Number: 1046

No database selected

INSERT INTO `your_stats` (`school`, `district`) VALUES ('TJHSST', 'FairFax') 

---

请尝试将密码留空

---

我认为这是WAMP和XAMPP的默认设置。它也可以用于MAMP。

我假设您正在自动加载数据库类

---

再次检查此项，并检查数据库名称是否正确。

No，不幸的是，在启动屏幕中，MAMP显式地将用户名和密码设置为root。您可能需要检查数据库名称。数据库名称与我在database.phpYes中列出的名称匹配，我有$autoload['libraries]=array'database'；数据库名stats_test与我通过MAMP在phpMyAdmin中创建的数据库名匹配。您的_stats应该是该数据库中的表。我是不是应该在MAMP里对phpMyAdmin做点特别的事？

$db['default']['hostname'] = "localhost:8889";
$db['default']['username'] = "root";
$db['default']['password'] = "root";
$db['default']['database'] = "stats_test";
$db['default']['dbdriver'] = "mysql";
$db['default']['dbprefix'] = "";
$db['default']['pconnect'] = TRUE;
$db['default']['db_debug'] = TRUE;
$db['default']['cache_on'] = FALSE;
$db['default']['cachedir'] = "";
$db['default']['char_set'] = "utf8";
$db['default']['dbcollat'] = "utf8_general_ci"; 

$config['base_url']    = "http://localhost:8888/ci/";
...
$config['index_page'] = "index.php";
...
$config['uri_protocol']    = "AUTO"; 

A Database Error Occurred
Error Number: 1046

No database selected

INSERT INTO `your_stats` (`school`, `district`) VALUES ('TJHSST', 'FairFax')