YII框架关联查询操作示例

本文实例讲述了YII框架关联查询操作。分享给大家供大家参考，具体如下：

以customer order两个表为例

关联查询控制器中

$customer = Customer::find()- where('name'= 'zhangsan')- one();
$orders = $customer- hasmany('orders',['customer_id']= 'id')- asArray()- all();
$orders = $customer- hasmany(Order::className(),['customer_id']= 'id')- asArray()- all();

customer模型中(优化)

public function getOrders(){
　　$orders = $this- hasmany('orders',['customer_id']= 'id')- asArray()- all();
}

关联查询控制器中就可以这么写

$customer = Customer::find()- where('name'= 'zhangsan')- one();
$orders = $customer- getOrders();

甚至可以这么写

$orders = $customer- orders;

当获取未定义的类属性时会触发类的__get()魔术方法效果 YII会自动调用 getOrders()方法，而且会加上- all(),所以定义getOrders()时不能带上all()

Order模型

public function getCustomer(){
　　$this- hasOne(Customer::className,['id'= 'customer_id'])- asArray();
}

关联查询控制器中这么写

$order = Order::find()- where("id"= '1')- one();
$customer = $order- customer;

注意点

1.关联查询会被缓存

所以

$customer = Customer::find()- where('name'= 'zhangsan')- one();
unset($customer- orders);//清掉缓存
$order = $customer- orders;

2.关联查询的多次查询

$customers = Customer::find()- all();//select * from customer
foreach($customers as $customer){
$order = $customer- orders;//select * from order where customer_id = ...
}

以上代码执行了101次sql查询，可以进行如下优化

$customers = Customer::find()- with('orders')- all();//select * from customer
foreach($customers as $customer){
$order = $customer- orders();//select * from order where customer_id in (...)
}//变成了2次查询