ActiveRecord

查询：

// find the customers whose primary key value is 10
$customers = Customer::findAll(10);
$customer = Customer::findOne(10);

// the above code is equivalent to:
$customers = Customer::find()->where(['id' => 10])->all();

// find the customers whose primary key value is 10, 11 or 12.
$customers = Customer::findAll([10, 11, 12]);
$customers = Customer::find()->where(['IN','id',[10,11,12]])->all();

// the above code is equivalent to:
$customers = Customer::find()->where(['id' => [10, 11, 12]])->all();

// find customers whose age is 30 and whose status is 1
$customers = Customer::findAll(['age' => 30, 'status' => 1]);

// the above code is equivalent to:
$customers = Customer::find()->where(['age' => 30, 'status' => 1])->all();

// use params binding
$customers = Customer::find()->where('age=:age AND status=:status')->addParams([':age'=>30,':status'=>1])->all();

// use index
$customers = Customer::find()->indexBy('id')->where(['age' => 30, 'status' => 1])->all();

// get customers count
$count = Customer::find()->where(['age' => 30, 'status' => 1])->count();

// add addition condition
$customers = Customer::find()->where(['age' => 30, 'status' => 1])->andWhere('score > 100')->orderBy('id DESC')->offset(5)->limit(10)->all();

// find by sql
$customers = Customer::findBySql('SELECT * FROM customer WHERE age=30 AND status=1 AND score>100 ORDER BY id DESC LIMIT 5,10')->all();

修改：

// update status for customer-10
$customer = Customer::findOne(10);
$customer->status = 1;
$customer->update();

// the above code is equivalent to:
Customer::updateAll(['status' => 1], 'id = :id',[':id'=>10]);

删除：

// delete customer-10
Customer::findOne(10)->delete();

// the above code is equivalent to:
Customer::deleteAll(['status' => 1], 'id = :id',[':id'=>10]);

使用子查询

$subQuery = (new Query())->select('COUNT(*)')->from('customer');

// SELECT `id`, (SELECT COUNT(*) FROM `customer`) AS `count` FROM `customer`
$query = (new Query())->select(['id', 'count' => $subQuery])->from('customer');

手写SQL

// select
$customers = Yii::$app->db->createCommand('SELECT * FROM customer')->queryAll();

// update
Yii::$app->db->createCommand()->update('customer',['status'=>1],'id=10')->execute();

// delete
Yii::$app->db->createCommand()->delete('customer','id=10')->execute();

//transaction
// outer 
$transaction1 = $connection->beginTransaction();
try {
    $connection->createCommand($sql1)->execute();

    // internal
    $transaction2 = $connection->beginTransaction();
    try {
        $connection->createCommand($sql2)->execute();
        $transaction2->commit();
    } catch (Exception $e) {
        $transaction2->rollBack();
    }

    $transaction1->commit();
} catch (Exception $e) {
    $transaction1->rollBack();
}