PHP脚本未将值插入到mySQL数据库中

Question

my insert isnt working, It ownt insert anything into the DB no matter what.

$sql= "INSERT INTO 'users' (`id`, `username`, `password`) VALUES (NULL,   '$newusername', '$newpassword')";

What did i do wrong? :( And yes i have connected to the DB earlier in the script.

Edit: Heres my whole .php

<?php
if (isset($_POST['submit'])){

    $newusername = $_POST['newusername'];
    $newpassword = $_POST['newpassword'];
    $newpassword2 = $_POST['confirmnewpassword'];

    $query = "SELECT * FROM users WHERE username = '$newusername' AND password = '$newpassword'";
if(strlen($newusername) > 5 || strlen($newusername)< 25){
echo "username length check is fine<br>";
    if(strlen($newpassword) > 4 || strlen($newpassword2) < 25){
        echo "Pass check worked lel<br>";
        if($newpassword == $newpassword2 ){
            echo "Should all be working!<br>";
            $connect = mysqli_connect("localhost","root","") or die("Couldnt connect!");
            mysqli_select_db($connect,"phplogin") or die("Couldnt find DB.");

            $sql="INSERT INTO users (username,password) VALUES('$newusername','$newpassword')";


        }
        else
            die("Passwords did not match");
    }
    else
        die('Password wasnt long enough');
}
    else
        die("Username was not long enough");

}

Sorry for the messy code. i get a feeling ive left something very obvious out.

Answer 1

At the PHP level:

In PHP you should make a habbit of setting up error levels to let you know when things become weird:

error_reporting(E_ALL);
ini_set('display_errors', true);
ini_set('scream.enabled', false);

With these settings you'll start seeing some PHP errors such as trying to access the contents of arrays that you expect to be populated by the DB but in fact are not (and they may not even be arrays). These are tip-offs to get you thinking that an SQL query has failed for some reason.

At the DB level:

Most likely you database is telling you exactly what is going on, you're just not checking what it's saying. Errors from the database manifest themselves in 3 ways: empty results, false instead of expected result, an error message available to you if you check for it.

Check for errors after each step:

• connect to DB;
• select DB (in case you're using mysql_* or mysqli_* functions);
• prepare statement (in case you're using mysqli_ or PDO );
• execute query;

I will assume you're using mysqli_* functions and give an example (original here ):

/** somewhere in the DB connection file */
$mysqlErrors = array();

/*...*/

/** somewhere in your logic files */
$rows = mysqli_query($link, "SET a=1");
if ($rows === false) {
    $mysqlErrors[] = mysqli_error($link);
}

/*...*/

/** somewhere in your template files */
foreach ($mysqlErrors as $mysqlError) {
    printf("Errormessage: %s\n", $mysqlError);
}

Answer 2

(1) do this,  id as auto increment then no need to include at insert time 

$sql= "INSERT INTO 'users' ( `username`, `password`) VALUES ('$newusername', '$newpassword')";

Answer 3

$sql= "INSERT INTO 'users' ( `username`, `password`) VALUES ('$newusername', '$newpassword')";

// add the following code below the line above

$result = mysqli_query($con, $sql);

Answer 4

Use Apostrophe instead of Grave accent ` = Grave accent, or (because someone needed to invent a word) backtick ' = Apostrophe, or straight single quote

(`id`, `username`, `password`)

You should use this

('id', 'username', 'password')