Question

我用php写了一个类，但是总是报错，mysqli_select_db() expects parameter 1 to be mysqli，怎么回事呢？

<?php
class Connection
{
protected $link;
private $server, $username, $password, $db;

public function __construct($server, $username, $password, $db)
{
$this->server = $server;
$this->username = $username;
$this->password = $password;
$this->db = $db;
$this->connect();
}

private function connect()
{
$this->link = mysql_connect($this->server, $this->username, $this->password);
$ret = mysqli_select_db($this->db, $this->link);
if($ret){
echo "成功连接";
}else{
echo "连接失败";
}
}

public function __sleep()
{
return array('server', 'username', 'password', 'db');
}

public function __wakeup()
{
$this->connect();
}
}
$p = new Connection('lcoalhost','root','111','testapp');
?>

Answer 1

如果我没记错的话，
mysqli_select_db 的参数顺序和 mysql_select_db相反吧， 先link 再 数据表
两类函数不能混着用吧？现在都推荐使用mysqli 这个扩展了

Answer 2

mysqli_select_db 改为 mysql_select_db