使用PHP将数据输入数据库

Question

为什么即使我已经将系统与数据库连接，错误仍然显示“插入新数据时出错”？数据甚至无法上传到数据库。

<?php

$newrecord = "";

include('db_novel.php');

if (isset($_POST['submitted'])){
    
    
    $novel_title = $_POST['novel_title'];
    $chapter = $_POST['chapter'];
    $genre = $_POST['genre'];
    $language = $_POST['language'];
    $synopsis = $_POST['synopsis'];
    $insert = "INSERT INTO novels (novel_title, chapter, genre, language, synopsis) VALUES ('$novel_title','$chapter','$genre','$language','$synopsis')";
    
    
    if (!mysqli_query($con, $insert)){
        die('error inserting new record');
    }//end of nested if statement
    
    $newrecord = "Successfully submitted!";
}//end of the main if statement
  
?>