声明活动记录类

namespace app\models;

use yii\db\ActiveRecord;

class Customer extends ActiveRecord
{
    
    public static function tableName()
    {
        return "customer";  // 没有设置表前缀时
        return "{{%customer}}"; // 设置表前缀时
    }
}

查询数据

1. 查询单条

   Model::find()->one();
   Model::findOne($id);
   Model::findOne($where);
   

2. 查询多条

   Model::find()->all();
   Model::find()->findBySql($sql)->all();
   Model::find()->findAll($ids);
   Model::find()->findAll($where);
   

3. 查询统计

   Model::find()->count();
   

4. 查询集合

   Model::find()->indexBy('id')->all();
   

• 查询可加入条件

  $model->where($where)->orderBy($order)->asArray()->batch()->each()->with();
  
  where 查询条件
  orderBy 排序
  asArray 返回数组格式的数据
  batch 限制查询条数
  with 关联查询
  

关联查询

class Customer extends \yii\db\ActiveRecord
{
    public function getOrders()
    {
        // Customer has_many Order via Order.customer_id -> id
        return $this->hasMany(Order::className(), ['customer_id' => 'id']);
    }
}

class Order extends \yii\db\ActiveRecord
{
    // Order has_one Customer via Customer.id -> customer_id
    public function getCustomer()
    {
        return $this->hasOne(Customer::className(), ['id' => 'customer_id']);
    }
}

完成上述声明后，就可以通过定义相应的getter方法来像访问对象属性一样获取关联数据：

// get the orders of a customer
$customer = Customer::findOne(1);
$orders = $customer->orders;  // $orders is an array of Order objects

提示：如果你再次访问 $customer->orders ，并不会重复执行上述第2行SQL查询。这条查询语句只在表达式第一次被访问时才被执行。后续的访问将直接返回内部缓冲数据。如果你想重新执行查询，只需要先调用一下unset来清除缓存: unset($customer->orders);

事务

$transaction = Yii::$app->db->beginTransaction(); // 启用事务
try {
    Article::find()->all();
    Admin::findOne(1);
    // ... executing other SQL statements ...
    $transaction->commit(); // 提交事务
} catch (Exception $e) {
    $transaction->rollBack(); // 事务回滚
}