PHP将数据从表单输入到SQL数据库中

Hello I wish to input some data from a HTML form in my website into a SQL database. Here is my database so far.

You could easily just call the addNewUser() function passing the required parameters as:

addNewUser($connect,$username,$password,$dbtable);

A better usage example would be to first check that the form has been already submitted to prevent any direct access or empty records and PHP warnings by checking that form fields have been submitted, ie.

if(isset($_POST["username"]) && isset($_POST["password"]))
{
    $username=$_POST['username'];
    $password=$_POST["password"];

    addNewUser($connect,$username,$password,$dbtable);
 }

Other than that this seems to be a very basic example and also a bad practise on how to implement a new insert in the database so be sure not to use any of this in a production environment. IE:

• No input filtering.
• Trying to "imitate" an Auto Increment field for the user
• Vulnerable to SQL injection and even prone to fail by accident if say a user tries to register with a username or password that contains a quote