wont store user input in the database using php - php

Question

the problem is only the password is stored but the rest doesnt...
this is the php code
<?php
define('DB_NAME','my_db');
define('DB_USER','root');
define('DB_PASSWORD','123');
define('DB_HOST','localhost');
$link = mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);
$firstname = isset($_POST['fname']) ? $_POST['fname'] : '';
$lastname =isset($_POST['lname']) ? $_POST['lname'] : '';
$email = isset($_POST['email']) ? $_POST['email'] : '';
$bday = isset($_POST['bday']) ? $_POST['bday'] : '';
$gender = isset($_POST['gender']) ? $_POST['gender'] : '';
$pass = isset($_POST['password']) ? $_POST['password'] : '';
$submit = isset($_POST['submit']) ? $_POST['submit'] : null;
$sql = "INSERT INTO user(fname,lname,email,bday,gender,password)
VALUES ('$firstname','$lastname','$email','$bday','$gender','$pass')";
if(!mysql_query($sql)){
die('Error: ' . mysql_error());
}
mysql_close();
?>
this is the html code
<form action="connect.php" method="post">
First name: <input type="password" name="fname">
Last name: <input type="text" name="lname"><br><br>
Email Address: <input type="email" name="email"><br><br>
Birthday: <input type="date" name="bday">
Sex: <input list="Sex" name="gender">
Password: <input type="password" name="password"><br><br>
<datalist id="Sex">
<option value="Male">
<option value="Female">
</datalist><br><br>
<input type="submit" value="Sign up!" id="btnsignup" />
</form>
*data types in the table are: fname is varchar, lname is varchar, email is varchar, bday is date, gender is char, password is char *

Answer 1

First of all, your HTML can only be used with the newest browsers. Try this instead to support older browsers (perhaps you've got one too and that is the problem):
<form action="connect.php" method="post">
First name: <input type="text" name="fname">
Last name: <input type="text" name="lname"><br><br>
Email Address: <input type="text" name="email"><br><br>
Birthday: <input type="text" name="bday" placeholder="YYYY-MM-DD">
Sex: <select name="gender">
<option value="Male">Male</option>
<option value="Female">Female</option>
</select>
Password: <input type="password" name="password"><br><br>
<input type="submit" value="Sign up!" id="btnsignup" />
</form>
You can use var_dump($_POST) or print_r($_POST) in the first line before all other code in your PHP script to check if the POST input from your HTML reaches the PHP.
As a alternative you can check the output of var_dump($_REQUEST), this array will contain GET and POST variables.
Double check if there is other PHP code executed before the one you've posted (redirects, manipulating $_POST vars and so on).
Also check if there are cookies, $_SERVER or ENV variables set with the variable names you have used.
In normal circumstances your example code should work.

Answer 2

Please check character limit of field in table or field name in table. I think there is the problem.