php - MySQLi insert_id()

Question

我不知道，我的代码有什么问题。我尝试获取最新的插入 ID，它正在回显 0。有什么想法吗？

public function __construct() {
  $this->mysqli = new mysqli(MYSQLI_SERVER, MYSQLI_USER, MYSQLI_PWD, MYSQLI_DBNAME) or die ('Error with connecting to the database!');;
}
public function insert_id(){
   return $this->mysqli->insert_id;  
}

$db->query("INSERT INTO user(f_name, l_name) VALUES('$f_name', '$l_name')");
var_dump($db->insert_id()); // return 0?

Answer 1

您应该按如下方式使用它:

<?php
$mysqli = new mysqli(SQLI_SERVER, MYSQLI_USER, MYSQLI_PWD, MYSQLI_DBNAME);
if ($result = $mysqli->query("INSERT INTO user(f_name, l_name) VALUES('$f_name', '$l_name');")) {
   echo 'The ID is: '.$mysqli->insert_id;
}
?>