尝试在表中插入值时，所有值都被清除

Question

I am trying to simply insert values into a database table using PHP. but every time all the pre-inserted values are getting erased and no value insertion takes place.

<?php
$servername = "localhost";
$username = "root";
$password = "rex";
$dbname = "test";
$usr = $_POST["Username"];
$pass = $_POST["password"];

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $sql = "INSERT INTO users(username,password)VALUES('$usr','$pass')";
    // use exec() because no results are returned
    $conn->exec($sql);
    echo "New record created successfully";
    }
catch(PDOException $e)
    {
    echo $sql . "<br>" . $e->getMessage();
}

$conn = null;
?>

Answer 1

This should work:

$sql = "INSERT INTO users (username, password) VALUES (?, ?)";
$prepared = $conn->prepare($sql);
$prepared->execute([$usr, $pass]);

This is also better since you are binding the variables.

http://php.net/manual/en/pdo.prepare.php

You should also sanitize your $_POST-variables. Username is also spelled with a capital U in your $_POST-variable.