Yii數據庫基本操作

1、單表查詢

<?php
namespace frontend\controllers;
use \yii\web\Controller;
use app\models\Test;
class HelloController extends Controller{
    public function actionIndex(){
        //查詢test表的數據
        $sql = 'select * from test where id = 1';
        //每條記錄包裝成對象，把對象包裝成數組返回
        //自帶防sql注入
        $result = Test::findBySql($sql)->all();
        print_r($result);
    }
}

簡便方法

$result = Test::find()
            ->where(['Id' => '2'])
            ->all();
        print_r($result);
//查詢id>0的數據
 $result = Test::find()
            ->where(['>','Id','0'])
            ->all();
        print_r($result);
//查詢id>= 1&&id<=2
$result = Test::find()
            ->where(['between','Id',1,2])
            ->all();
//title like "%title2"
        $result = Test::find()
            ->where(['like','title','title2'])
            ->all();

訪問http://lcc.com/index.php?r=hello/index可查詢結果
其他類型，訪問http://www.yiichina.com/doc/guide/2.0/db-active-record查詢

• 降低內存佔用

//對象方式返回很吃內存，所以Yii提供轉化數組的方法，asArray（）
        $result = Test::find()
            ->where(['>','Id','0'])
            ->asArray()
            ->all();

• //批量查詢

     foreach (Test::find()->batch(2) as $result) {
            print_r($result);//一次查2條，結果放在$result中
        }

2、單表刪除

• //刪除數據

        $result = Test::find()->where(['Id' => '1'])->all();
        $result[0]->delete();
        Test::deleteAll('id>0');//刪除大於0的行，同時，也支持佔位符的功能

3、單表添加數據

• //插入數據

        $test = new Test();
        $test->Id = 'abc';
        $test->title = 'title3';

• //調用模型證rules驗證器驗證

     $test->validate();

• //如果輸入數據不合法，輸出‘data is error ’

      if($test->hasErrors()){
            echo 'data is error';
            die;
        }
        $test->save();

• 模型中的驗證器

    public function rules()
    {
        return [
            ['Id','integer'],
            ['title','string','length'=>[0,10]]
        ];
    }

4、單表數據修改

• // //修改數據

     $test = Test::find()
            ->where(['Id' => 5])
            ->one();
        $test->title = 'testtitle';
        $test->save();

5、關聯查詢

• //根據顧客查詢訂單的信息

       $customer = Customer::find()->where(['id'=>1])->one();
        //$order = $customer->hasMany('app\models\Order',['customer_id' => 'id'])->asArray()->all();
        $order = $customer->hasMany(Order::className(),['customer_id' => 'id'])->asArray()->all();
        print_r($order);

優化：

    $customer = Customer::find()->where(['id'=>1])->one();
        //$order = $customer->getOrder();
        $order = $customer->order;//原理：調用不存在的屬性時，默認調用$__GET方法，臉上order，進而調用getorder
        print_r($order);

在Customer中添加getOrder方法

    public function getOrder(){
        $order = $this->hasMany(Order::className(),['customer_id' => 'id'])->asArray()->all();
        return $order;
    }

• //根據訂單查詢顧客

      $order = Order::find()->where(['order_id'=>1])->one();
        $customer = $order->customer;
        print_r($customer);

在Order中添加getCustomer方法

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

6、關聯查詢性能問題

• 關聯查詢結果緩存
• 關聯查詢的多次查詢（用with（））