swoole与mysql怎么用才好

<?php
class mysql {
 private $param;
 public $db;
 public function __construct() {
 $this->db = new swoole_mysql;
 $this->param = array(
 'host' => '127.0.0.1',
 'user' => 'root',
 'password' => '123',
 'database' => 'test',
 );
 }

 public function exec($sql) {
 $this->db->connect($this->param, function ($db, $result) use ($sql) {
 if ($result === false) {
 echo "连接数据库失败 ： 错误代码：" . $db->connect_errno . PHP_EOL . $db->connect_error;
 return false;
 }
 $db->query($sql, function ($db, $res) {
 if ($res === false) {
 // error属性获得错误信息，errno属性获得错误码 
 echo "sql语句执行错误 : " . $db->error;
 } else if ($res === true) {
 // 非查询语句 affected_rows属性获得影响的行数，insert_id属性获得Insert操作的自增ID 
 echo "sql语句执行成功，影响行数 : " . $db->affected_rows;
 
 } else {
 //查询语句 $result为结果数组 
 var_dump($res);
 
 }
 $db->close();
 });
 });
 }
}

$mysql = new mysql();