yii框架数据库关联查询操作示例

<?php
namespace app\controllers;
use yii\web\Controller;
use app\models\Customer;
class CustomerController extends Controller{
  //根据顾客名字查询出所有的订单信息
  public function actionIndex(){
    $customer = Customer::find()->where(['name'=>'zhangsan'])->one();
    $orders = $customer->hasMany('app\models\Order',['customer_id'=>'id'])->asArray()->all();
    print_r($orders);
  }
}
?>

<?php
namespace app\models;
use yii\db\ActiveRecord;
class Customer extends ActiveRecord{
  public function getOrders(){
    return $this->hasMany(Order::className(),['customer_id'=>'id'])->asArray()->all();
  }
}

namespace app\controllers;
use yii\web\Controller;
use app\models\Customer;
class CustomerController extends Controller{
  //根据顾客名字查询出所有的订单信息
  public function actionIndex(){
    $customer = Customer::find()->where(['name'=>'zhangsan'])->one();
    $orders = $customer->getOrders();
    print_r($orders);
  }
}

namespace app\models;
use yii\db\ActiveRecord;
class Customer extends ActiveRecord{
  public function getOrders(){
    return $this->hasMany(Order::className(),['customer_id'=>'id'])->asArray();
  }
}

namespace app\controllers;
use yii\web\Controller;
use app\models\Customer;
class CustomerController extends Controller{
  //根据顾客名字查询出所有的订单信息
  public function actionIndex(){
    $customer = Customer::find()->where(['name'=>'zhangsan'])->one();
    $orders = $customer->orders;
    //说明，当调用一个不存在的属性时，
    //php会去调用一个__get()的方法，
    //__get()的方法会自动调用一个get+属性的方法，即getOrders()
    //并且会再查询时自动补上->all()或->one()方法,根据模型查询的hasMany或hasOne决定的
    print_r($orders);
  }
}

namespace app\models;
use yii\db\ActiveRecord;
class Order extends ActiveRecord{
  //根据订单id获取顾客信息
  public function getCustomer(){
    return $this->hasOne(Customer::className(),['id'=>'customer_id'])->asArray();
  }
}

namespace app\controllers;
use yii\web\Controller;
use app\models\Order;
class CustomerController extends Controller{
  //根据订单查询用户信息
  public function actionIndex(){
    $orders = Order::find()->where(['id'=>2])->one();
    $customer = $orders->customer;
    print_r($customer);
  }
}

$customers = Customer::find()->all();
foreach($customers as $customer){
  $orders = $customer->orders;
}

$customers = Customer::find()->with('orders')->all();
foreach($customers as $customer){
  $orders = $customer->orders;
}