PHP Form , session data not being stored

we are working with php session data, but the data is not being stored in the database

login.php

<h2>Welcome</h2>
<form action = "Customer.php" method = "POST">
 Customer Name:<input type = "text" name="customerName">
 <input type = "submit" name = "submit">
</form> 

Customer.php

<?php 

session_start(); 
#include("Connection.php);

if (isset($_POST['submit'])) { 
    $name = $_POST['customerName']; 
    $_SESSION['user'] = $name; 
} 
if (isset($_SESSION['user'])) 
{ 
    echo "Hello {$_SESSION['user']}, welcome to starbucks!"; 
}
else
{
    echo "walang tao";
    $sql="INSERT INTO  `customer`.`people` 开发者_C百科('ID', `NAME`) VALUES ('','$name')";
    mysql_query($sql);
?>
<a href = "logout.php">Logout</a>

and logout.php

<?php

session_start();
session_destroy();

?>

<a href = "index.php">Click me to return to login </a>

please tell me what's wrong

---

try displaying the mysql_error and see what the problem is

mysql_query($sql) or die(mysql_error());