class db{

private $dbConfig = [

'db' =>; 'mysql',

'主机' => 'localhost',

'端口' => '3306',

'数据库名称'=>  '一个',

'用户' => 'root',

'密码' => '1234',//

'字符集' => 'utf'

];

public $insertId = null;

public $num = 0;

私有静态 $instance =  null;

private $conn = null;

私有函数 __construct($params){

$this->dbConfig = array_merge($this->dbConfig,$params);

$this->conncet();

}

私有函数 __clone(){

}

公共函数 getInstance(){

if(!self::$instance instanceof self){

self::$instance = new self();

}

return self::$instance;

}

public function connect(){

try{

$dsn = "{$this->dbConfig['db']}:{$this ->dbConfig['host']};

port = {$this->dbConfig['port']};

字符集 = {$this->dbConfig['charset']}";

$this->conn = new pdo($dsn,$this->dbConfig['user'],$this->dbConfig['password']);

}

catch(PDOExecption $e){

die("数据库连接失败".$e->getMessage());

}

}

//完成数据表的写操作 新增更新

// 返回数据表的记录 如果新增还返回新增主键id

public function exec($sql){

$num = $this->conn->exec($sql);

// 如果有此次的记录

if($num>0){

// 如果是新增操作初始化新增主键ID的属性

if(null !==$this->conn->lastInsertId()){

$this ->insertId = $this->conn->lastInsertId();

}

$this->num = $rum;//返回旅行的记录

}else{

$error = $this->conn->errorInfo(); //获取最后操作的错误信息 【0】错误标识符【1】错误代码【2】错误信息

print '操作失败'.$error[0].':'.$error[1].': '.$error[2];

}

}

//获取单条查询信息

public function fetch ($sql )

{

return $this->conn->query ($sql)->fetch(PDO::FETCH_ASSOC);

}

public function fetchALL($sql){

return $this->conn->query($sql)->fetch( PDO::FETCH_ASSOC);

}

}