Codeigniter - 使用多个数据库

// 数据库连接 1
$db['default'] = array(
    'dsn'   => '',
    'hostname' => 'localhost',
    'username' => 'user1',
    'password' => 'password1',
    'database' => 'database1',
    'dbdriver' => 'mysqli',
    'dbprefix' => '',
    'pconnect' => FALSE,
    'db_debug' => (ENVIRONMENT !== 'production'),
    'cache_on' => FALSE,
    'cachedir' => '',
    'char_set' => 'utf8',
    'dbcollat' => 'utf8_general_ci',
    'swap_pre' => '',
    'encrypt' => FALSE,
    'compress' => FALSE,
    'stricton' => FALSE,
    'failover' => array(),
    'save_queries' => TRUE
);

// 数据库连接 2
$db['another_db'] = array(
    'dsn'   => '',
    'hostname' => 'localhost',
    'username' => 'user2',
    'password' => 'password2',
    'database' => 'database2',
    'dbdriver' => 'mysqli',
    'dbprefix' => '',
    'pconnect' => FALSE,
    'db_debug' => (ENVIRONMENT !== 'production'),
    'cache_on' => FALSE,
    'cachedir' => '',
    'char_set' => 'utf8',
    'dbcollat' => 'utf8_general_ci',
    'swap_pre' => '',
    'encrypt' => FALSE,
    'compress' => FALSE,
    'stricton' => FALSE,
    'failover' => array(),
    'save_queries' => TRUE
);

// 在控制器中使用 default 数据库连接
$this->load->database();

// 在模型中使用 another_db 数据库连接
$this->load->model('another_model', 'another_db');