MySQLi输入数据到数据库[重复]

How can I get my form to input the fields to my database using MySQLi (mysqli procedural) I currently have this but it goes though when I submit with no errors but nothing goes into the database.

 <?php

    if(isset($_POST["submit"])){
    $Fname = $_POST['firstname'];
    $Lname = $_POST['lastname'];
    $email = $_POST['email'];
    $gender = $_POST['gender'];
    $bday = $_POST['bday'];

$servername = "<--enter servername -->";
$username = "<--enter username -->";
$password = "<--enter password -->";
$database = "<--enter datbase name -->";

  // Create connection
  $conn = mysqli_connect($servername, $username, $password, $database);

    $sql = "INSERT INTO Questions_users (Fname, Lname, email, gender, bday)
    VALUES ('$Fname','$Lname','$email','$gender','$bday')";

    if (mysqli_query($conn, $sql)) {
    echo "New record created successfully";
    } else {
    echo "Error: " . $sql . "<br>" . mysqli_error($conn);
    }

    mysqli_close($conn);
    }
    ?>

And the form is

<form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post">
<input type="text" name="firstname"></td>
<input type="text" name="lastname"></td>
<input type="email" name="email"></td>
<input type="radio" name="gender" value="male" checked> Male<br>
<input type="radio" name="gender" value="female"> Female</td>
<input type="date" name="bday"></td>
<input type="submit" value="Submit"></form>

</div>

You'll need to set the name attribute for this:

<input type="submit" name="submit" value="Submit">

Your PHP code was not executed as you set the condition if(isset($_POST["submit"])){ and the submit element was not found.

Also, you've missed out the closing bracket:

$sql = "INSERT INTO Questions_users (Fname, Lname, email, gender, bday)
VALUES ('[$Fname]','[$Lname]','[$email','[$gender]','[$bday]')";

'[$email' should be '[$email]'.