I am looking for a script to check my database to see if a username is already in use. I am new to PHP so talk to me like I am 10 (even though a ten year old can probably program better than me). I just want to check the database and return a true or false based on a variable that is entered in my form below. Also, I want to use an AJAX request to make this happen so I don't know if that matters. Also I am using SQL Buddy.
<p><form action="/signup/register.php" method="post">
<label for="first_name">First Name</label>
<input type="text" name="first_name" />
<label for="last_name">Last Name</label>
<input type="text" name="last_name" />
<label for="company">Company</label>
<input type="text" name="company" />
<label for="job_title">Job Title</label>
<input type="text" name="job_title" />
<label for="phone">Phone</label>
<input type="text" name="phone" />
<label for="email">Email</label>
<input type="text" name="email" />
<label for="username">Choose a Username</label>
<input type="text" name="username" />
<label for="password">Choose a Password</label>
<input type="text" name="password" />
<label for="confirm_password">Confirm Your Password</label>
<input type="text" name="confirm_password" />
<input type="submit" value="Get Started" />
</form>