php 致命错误：调用未定义的函数 mysqli()
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Fatal error: Call to undefined function mysqli() in
提问by Rasim Fryal
I am instentiating $db object this way in my database class
我在我的数据库类中以这种方式实例化 $db 对象
class db{
private $connection;
public function __construct(){
$this->connect();
}
public function connect(){
$this->connection=mysqli_connect('localhost','root','','new5');
}
}
$db=new db;
I am using this $db object in another class(profile class) as link identifier as
我在另一个类（配置文件类）中使用这个 $db 对象作为链接标识符
$query=$db->query("SELECT id, parent_id, name FROM categories_general");
Please help me ,how can i get rid of this error.Actually I am recently shifted from mysql to mysqli.
请帮助我，我怎样才能摆脱这个错误。实际上，我最近从 mysql 转移到了 mysqli。
回答by case1352
try
尝试
$db = mysqli_connect('localhost','root','XXX','XXX');
回答by Xingjia Luo
$db = new mysqli('localhost','root','','test');
$sql = "select * from user";
$result = $db->query($sql);
var_dump($result->fetch_assoc());
回答by zenon
You are using procedural style of mysqli. So you must create query method in db class.
您正在使用 mysqli 的程序风格。所以你必须在 db 类中创建查询方法。
class db{
private $connection;
public function __construct(){
$this->connect();
}
public function connect(){
$this->connection=mysqli_connect('localhost','root','','new5');
}
//add these methods
public function query($query_string){
return mysqli_query($this->connection, $query_string);
}
public function fetch_row($mysqli_result){
return mysqli_fetch_row($this->connection, $mysqli_result);
}
//and other functions you need
}
or you can use object oriented style with extends method;
或者您可以使用带有扩展方法的面向对象样式；
class db extends mysqli{
function __construct($host, $username, $password, $databaseName, $port=3306){
mysqli::__construct($host, $username, $password, $databaseName, $port);
}
}
回答by Xingjia Luo
add a function
添加功能
public function getDB()
{
return $this->_mysql;
}
$query=mysqli_query($db->getDB(),"SELECT id, parent_id, name FROM categories_general");
