如何在插入新记录时获取最后插入的记录ID？

Question

我正在尝试从数据库获取新插入的记录ID，但始终返回0值。 在数据库中，我有2条记录，所以当我插入新记录时，我想要新记录ID 3，但我得到0。 在我的代码下面，我尝试获取ID

<?php
class User extends Database{
    public function candidateRegister($name,$email,$pass){
        $data = '';

        $query = $this->connect()->query("INSERT INTO user(username, useremail, userpass) VALUES('$name','$email','$pass')");
        if($query == true){
            $data = $this->connect()->insert_id;
        }else{
            $data = 'Something went wrong';
        }
        return $data;
    }
}
?>

在我的数据库连接代码下面

<?php
class database{
    private $servername;
    private $username;
    private $password;
    private $dbname;

    protected function connect(){
        $this->servername = 'localhost';
        $this->username = 'root';
        $this->password = '';
        $this->dbname = 'mytable';
        $conn = new mysqli($this->servername, $this->username, $this->password, $this->dbname);
        return $conn;
    }
}

？>

Answer 1

确保表中有自动递增和主键。