mysqli not Fount in wamp

Hi, I have wamp installed, but when I run a connection, it does not work for me, it says it does not work. mysqli

private function connectDB(){
    $this->link = new mysqli($this->host, $this->user, $this->pass, $this->dbname);
    if(!$this->link){
        $this->error ="Connection fail".$this->link->connect_error;
        return false;
    }

  

Error

Fatal error: Class 'mysqli' not found