我的PHP注册表不起作用

Question

I have created a signup form for my php website using Bootstrap but nothing happens when I click on register. Signup form is made in Bootstrap and it is not working.

    <div class="container">

<div class="row">
    <div class="col-xs-12 col-sm-8 col-md-6 col-sm-offset-2 col-md-offset-3">
    <?php
require_once("company-db.php");
if (!isset($_POST['submit'])) {
?> 
        <form role="form" action="<?=$_SERVER['PHP_SELF']?>" method="post">
            <h2>Please Sign Up <small>It's free and always will be.</small></h2>
            <hr class="colorgraph">
            <div class="row">
                <div class="col-xs-12 col-sm-6 col-md-6">
                    <div class="form-group">
                        <input type="text" name="username" id="username" class="form-control input-lg" placeholder="Username" tabindex="1">
                    </div>
                </div>
                <div class="col-xs-12 col-sm-6 col-md-6">
                    <div class="form-group">
                        <input type="password" name="password" id="password" class="form-control input-lg" placeholder="Password" tabindex="2">
                    </div>
                </div>
            </div>
            <div class="form-group">
                <input type="text" name="company_name" id="company_name" class="form-control input-lg" placeholder="Company Name" tabindex="3">
            </div>
            <div class="form-group">
                <input type="text" name="description" id="description" class="form-control input-lg" placeholder="Company Description" tabindex="4">
            </div>
            <div class="form-group">
                <input type="email" name="email" id="email" class="form-control input-lg" placeholder="Email Address" tabindex="4">
            </div>
            <div class="row">
                <div class="col-xs-4 col-sm-3 col-md-3">
                    <span class="button-checkbox">
                        <button type="button" class="btn" data-color="info" tabindex="7">I Agree</button>
                        <input type="checkbox" name="t_and_c" id="t_and_c" class="hidden" value="1">
                    </span>
                </div>
                <div class="col-xs-8 col-sm-9 col-md-9">
                     By clicking <strong class="label label-primary">Register</strong>, you agree to the <a href="#" data-toggle="modal" data-target="#t_and_c_m">Terms and Conditions</a> set out by this site, including our Cookie Use.
                </div>
            </div>

            <hr class="colorgraph">
            <div class="row">
                <div class="col-xs-12 col-md-6"><input type="submit" value="submit" class="btn btn-primary btn-block btn-lg" tabindex="7"></div>
                <div class="col-xs-12 col-md-6"><a href="login.php" class="btn btn-success btn-block btn-lg">Sign In</a></div>
            </div>
        </form>
        <?php
} else {
## connect mysql server
    $mysqli = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);
    # check connection
    if ($mysqli->connect_errno) {
        echo "<p>MySQL error no {$mysqli->connect_errno} : {$mysqli->connect_error}</p>";
        exit();
    }
## query database
    # prepare data for insertion
    $username    = $_POST['username'];
    $password    = $_POST['password'];
    $company_name    = $_POST['company_name'];
    $description    = $_POST['description'];
    $email        = $_POST['email'];

    # check if username and email exist else insert
    $exists = 0;
    $result = $mysqli->query("SELECT username from companies WHERE username = '{$username}' LIMIT 1");
    if ($result->num_rows == 1) {
        $exists = 1;
        $result = $mysqli->query("SELECT email from companies WHERE email = '{$email}' LIMIT 1");
        if ($result->num_rows == 1) $exists = 2;    
    } else {
        $result = $mysqli->query("SELECT email from companies WHERE email = '{$email}' LIMIT 1");
        if ($result->num_rows == 1) $exists = 3;
    }

    if ($exists == 1) echo "<p>Username already exists!</p>";
    else if ($exists == 2) echo "<p>Username and Email already exists!</p>";
    else if ($exists == 3) echo "<p>Email already exists!</p>";
    else {
        # insert data into mysql database
        $sql = "INSERT  INTO `companies` (`id`, `username`, `password`, `company_name`, `description`, `email`)
                VALUES (NULL, '{$username}', '{$password}', '{$company_name}', '{$description}', '{$email}')";

        if ($mysqli->query($sql)) {
            //echo "New Record has id ".$mysqli->insert_id;
            echo "<p>Registred successfully!</p>";
        } else {
            echo "<p>MySQL error no {$mysqli->errno} : {$mysqli->error}</p>";
            exit();
        }
    }
}
?>        
    </div>
</div>

Answer 1

You don't have a name for your submit button, so this won't get posted.

<input type="submit" value="submit" name="submit"
       class="btn btn-primary btn-block btn-lg" tabindex="7">

Give the name attribute and make it set.

Note: You must never rely on <kbd>Submit</kbd> button's attribute!

---

The (!isset($_POST['submit'])) conditional statement depends on the execution of your code.