将数据插入MySQL时500内部服务器

I am attempting to test my database by inserting some basic data into a MySQL database, but I keep getting an error. After checking with Advanced Rest Client, it tells me it's a 500 Internal Server Error. I can't seem to figure out what i'm doing wrong at this point. This is my PHP Code

<?php

//redacted password
$con = mysqli_connect("localhost", "root", "mypass", "user_data");

if (mysqli_connect_errno()) {
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$firstname          = "John";
$lastname           = "Smith";
$email              = "email@domain.com";
$password           = "testpass";
$uuid               = uniqid('', true);
$hash               = $this->hashSSHA($password);
$encrypted_password = $hash["encrypted"]; // encrypted password
$salt               = $hash["salt"]; // salt

$sql = mysqli_query($con, "INSERT INTO userinfo_basic(userid, firstname, lastname, email, encrypted_password, salt, created_at) VALUES('$uuid', '$firstname', '$lastname' '$email', '$encrypted_password', '$salt', NOW())");

if ($sql == true) {

    echo "User Successfully Added!";

} else {

    echo "User could not be added";

}



mysqli_close($con);

?>

If there's anything I need to change or add, please ask. All Help is appreciated!

You've missed a comma after '$lastname'.

Change:

INSERT INTO userinfo_basic(userid, firstname, lastname, email, encrypted_password, salt, created_at) VALUES('$uuid', '$firstname', '$lastname' '$email', '$encrypted_password', '$salt', NOW())

To:

INSERT INTO userinfo_basic(userid, firstname, lastname, email, encrypted_password, salt, created_at) VALUES('$uuid', '$firstname', '$lastname', '$email', '$encrypted_password', '$salt', NOW())