Detailed Guide to the Basic Usage of the mysql_pconnect Function: Do You Know How to Use It for Persistent Connections?

When working with PHP and MySQL databases, developers often need to frequently establish and close database connections. For high-traffic sites, this repetitive process not only increases server load but also impacts overall performance. To solve this problem, PHP provides the mysql_pconnect() function.

• : Database host address, which can include the port number.


• $username: Database username.


• $password: Database password.


• $client_flags: Optional parameter for setting client flags.

Code Example

<br>
<?php<br>
// Connect to the database using persistent connection<br>
$link = mysql_pconnect("localhost", "root", "password");</p>
<p>if (!$link) {<br>
die("Connection failed: " . mysql_error());<br>
} else {<br>
echo "Persistent connection successful!";<br>
}</p>
<p>// Select database<br>
mysql_select_db("test_db", $link);</p>
<p>// Execute query<br>
$result = mysql_query("SELECT * FROM users");</p>
<p>while ($row = mysql_fetch_assoc($result)) {<br>
echo $row['username'] . "<br>";<br>
}<br>
?><br>

Notes on Persistent Connections

1. Resource Usage: Persistent connections are not closed when the script ends. Too many connections can exhaust server resources.


2. Connection State: When reusing a connection, note that it may not be in its default state (e.g., uncommitted transactions). Always initialize before use.


3. Deprecation Risk: mysql_pconnect() is part of the deprecated MySQL extension and has been removed as of PHP 7. It is recommended to use mysqli or PDO for persistent connections instead.

Alternative Solutions

Since mysql_pconnect() is deprecated, it is recommended to use the mysqli extension with mysqli_connect() and the p: prefix for persistent connections, or use PDO with PDO::ATTR_PERSISTENT enabled. These approaches ensure compatibility with newer PHP versions while providing more features and better security.

Conclusion: While mysql_pconnect() can improve database performance in certain cases, due to its deprecation and resource management concerns, it is strongly recommended to use persistent connections with mysqli or PDO in real-world projects.