Multiple Databases Connection on yii2

问题:

I'm trying to use multiple database connection on yii2 framework. Under my db.php file inside the config folder, I have this piece of code:

return [
    'class' => 'yii\db\Connection',
    'components' => [
        'db1' => [
            'class' => 'yii\db\Connection',
            'dsn' => 'mysql:host=localhost;dbname=new',
            'username' => 'root',
            'password' => 'password',
            'charset' => 'utf8',
        ],
        'db2' => [
            'class' => 'yii\db\Connection',
            'dsn' => 'mysql:host=localhost;dbname=old',
            'username' => 'root',
            'password' => 'password',
            'charset' => 'utf8',
        ],
    ],
];

In my test.php under the models folder, I have this below...

namespace app\models;

use Yii;
use yii\base\Model;
use yii\db\Query;

class GetAds extends Model
{
    public function ads()
    {

        $test = Yii::$app->db1->createCommand((new \yii\db\Query)->select('*')->from('members'))->queryAll();

    }

when I try to access, I get this error message "Getting unknown property: yii\web\Application::db1"

How do I solve this problem ? I've actually followed this guide Multiple database connections and Yii 2.0

Where have I done wrong ?

The worst thing is, I've set to use just one database... and on my model, I use this code..

    namespace app\models;

    use Yii;
    use yii\base\Model;
    use yii\db\ActiveRecord;
    use yii\db\Query;

    class GetAds extends ActiveRecord
    {
        public static function tableName()
        {
            return 'ads_page';
        }

        public static function ads()
        {

            $count=(new \yii\db\Query)->from('ads_page')->count('*'); 
    }
}

And I get this error

Database Exception – yii\db\Exception
could not find driver
↵
Caused by: PDOException
could not find driver

Why is using yii2 so hard ? I've follow all from here http://www.yiiframework.com/doc-2.0/guide-db-dao.html

please help

回答1:

I've solved this problem. This might help others who need this.

Under config/web.php, I added this line "'db2' => require(__DIR__ . '/db2.php')," just under this statement "'db' => require(__DIR__ . '/db.php')," (without quotes)

and created another new db2.php file under the config folder using the same codes as in db.php:

<?php

return [
    'class' => 'yii\db\Connection',
    'dsn' => 'mysql:host=localhost;dbname=test2',
    'username' => 'root',
    'password' => 'password',
    'charset' => 'utf8',
];

and to call the first database. I use this:

$row = Yii::$app->db->createCommand("SELECT * FROM test")->queryOne(); 

To query table from the second database, I use this:

$row = Yii::$app->db2->createCommand("SELECT * FROM test2")->queryOne();

回答2:

1. Make sure you have the php_mysql and php_pdo_mysql extensions installed.
2. The \yii\db\ActiveRecord class should know what database it's working with

This is the code to you add to the model to make it aware of its database.

public static function getDb()
{
    return Yii::$app->get('db1');
}

回答3:

You can also do this:

new User(array("db" => Yii::$app->db1));

or do this:

User::find()->where(...)->all(Yii::$app->db2);