创建一个类

class DB_class
{//public $name = 'andy';//私有的属性private static $db;//公共的静态方法public static function index(){if (self::$db != null ){return self::$db;}self::$db=new DB_class();return self::$db;}//私有的构造方法private function __construct(){}//私有的克隆方法private function __clone(){// TODO: Implement __clone() method.}/*** @return mixed* 查询*/public function query($sql){//连接数据库$my = mysqli_connect('127.0.0.1','root','root','zhuangao_six');//选择字符集mysqli_set_charset($my,'utf8');//执行$res=mysqli_query($my,$sql);$data=mysqli_fetch_all($res,1);mysqli_free_result($res);return  $data;mysqli_close($my);}//增删改function zsg($sql){//连接数据库$my = mysqli_connect('127.0.0.1','root','root','zhuangao_six');//选择字符集mysqli_set_charset($my,'utf8');//执行$res=mysqli_query($my,$sql);
//        $data=mysqli_fetch_all($res,1);
//        mysqli_free_result($res);
//        return  $data;return $res;mysqli_close($my);}
}

使用

//测试新增方法function db(){$db = DB_class::index();//$sql = "select * from owner";$sql = "INSERT INTO owner ( name, age ,sex ) VALUES( 'zhang1', '12','男' )";$data = $db->zsg($sql);}//查找方法function db(){$db = DB_class::index();$sql = "select * from owner";//$sql = "INSERT INTO owner ( name, age ,sex ) VALUES( 'zhang1', '12','男' )";$data = $db->query($sql);}//删除方法function db(){$db = DB_class::index();$sql = "DELETE FROM owner WHERE id = '1'";$data = $db->zsg($sql);}//修改方法function db(){$db = DB_class::index();$sql = "UPDATE owner SET name='lalal', age='2' WHERE id=2";$data = $db->zsg($sql);}