未定义的变量$ submit

Question

I'm getting an error which states: Notice: Undefined variable: submit on line 4. I have no clue why since I have defined it with the submit button? Can someone please explain why? Don't really see the problem here.

<?php

                if($submit)
                {
                $sql = "INSERT INTO personnel (first, last, username, department, email) VALUES ('$first','$last','$username','$department','$email')";
                $add = mysql_query($sql);
                echo "<div class='confirmation-box round'>Thank you! New user have been added</div>";
                }
                else
                {
                ?>
                <form method="post" action="useradd.php">

                    <fieldset>

                    <p>
                        <label for="simple-input">Firstname</label>
                        <input type="text" id="first" name="firstname" class="round default-width-input" />
                    </p>
                    <p>
                        <label for="simple-input">Lastname</label>
                        <input type="text" id="last" name="lastname" class="round default-width-input" />
                    </p>
                    <p>
                        <label for="simple-input">Username</label>
                        <input type="text" id="username" name="username" class="round default-width-input" />
                    </p>
                    <p>
                        <label for="simple-input">Department</label>
                        <input type="text" id="department" name="department" class="round default-width-input" />
                    </p>
                    <p>
                        <label for="simple-input">Email</label>
                        <input type="text" id="email" name="email" class="round default-width-input" />
                    </p>
                        <input type="Submit" name="submit" class="button round blue image-right ic-add text-upper" value="Add">

                    </fieldset>

                </form>
                <?php
                }
                ?>

(Sorry for stupid question, kinda new at php)

Answer 1

This is a typical old school case of register_globals usage. It decides whether or not register the EGPCS (Environment, GET, POST, Cookie, Server) variables as global variables. Nobody does that anymore.

Change it to this:

if (!empty($_POST['submit'])) {