What are the differences between mysql_connect() and mysql_pconnect() in PHP and how do they impact database connections?

The main difference between mysql_connect() and mysql_pconnect() in PHP is that mysql_connect() opens a new connection to the database each time it is called, while mysql_pconnect() opens a persistent connection that is not closed when the execution of the script ends. Persistent connections can improve performance by reducing the overhead of establishing a new connection each time a script is run, but they can also lead to resource exhaustion if not managed properly. To address this issue, it is recommended to use mysql_connect() for most cases to ensure that connections are properly closed and resources are released after each script execution. Only use mysql_pconnect() when there is a clear performance benefit and when the potential drawbacks, such as resource exhaustion, have been considered.

// Using mysql_connect() to establish a non-persistent database connection
$host = 'localhost';
$user = 'username';
$password = 'password';
$database = 'database';

$conn = mysql_connect($host, $user, $password);
if (!$conn) {
    die('Could not connect: ' . mysql_error());
}

mysql_select_db($database, $conn);

// Perform database operations

mysql_close($conn); // Close the connection after use