先创建连接对象
$connection = new \yii\db\Connection([
'dsn' => $dsn,
'username' => $username,
'password' => $password,
]);
$connection->open();
//查询返回多行:
$command = $connection->createCommand('SELECT * FROM post');
$posts = $command->queryAll();
//返回单行:
$command = $connection->createCommand('SELECT * FROM post WHERE id=1');
$post = $command->queryOne();
//查询多行单值:
$command = $connection->createCommand('SELECT title FROM post');
$titles = $command->queryColumn();
//查询标量值/计算值:
$command = $connection->createCommand('SELECT COUNT(*) FROM post');
$postCount = $command->queryScalar();
打印出AR模式下的sql语句
$coupon = new Coupon;
$coupon = $coupon->find();
var_dump($coupon->createCommand()->getRawSql());
exit;