In this guide, we will walk you through the process of resolving the "Call to Undefined Function mysql_pconnect()" error that you might encounter while working on a PHP project. This error occurs when you try to use the mysql_pconnect() function, which has been deprecated since PHP 5.5.0 and removed in PHP 7.0.0.

To fix this error, we will discuss the following steps:

1. Understanding the mysql_pconnect() error
2. Replacing mysql_pconnect() with mysqli or PDO
3. Updating your database connection code
4. Testing the updated code

1. Understanding the mysql_pconnect() error

The mysql_pconnect() function was used in older versions of PHP to establish a persistent connection to a MySQL database. However, this function was deprecated in PHP 5.5.0 and completely removed in PHP 7.0.0, meaning that it is no longer available for use in newer PHP versions.

If you are using a PHP version older than 5.5.0, it is highly recommended that you upgrade to a newer version, as older versions are no longer supported and may have security vulnerabilities. You can check your PHP version by running the following command in your terminal:

php -v

2. Replacing mysql_pconnect() with mysqli or PDO

To replace mysql_pconnect(), you can use either the MySQLi (MySQL Improved) extension or the PDO (PHP Data Objects) extension. Both of these extensions offer better performance, improved security, and support for prepared statements.

MySQLi

MySQLi is an extension specifically designed for working with MySQL databases. It provides both procedural and object-oriented interfaces and supports prepared statements, transactions, and more.

To use MySQLi, you need to replace your mysql_pconnect() function with the mysqli_connect() function. The syntax for mysqli_connect() is as follows:

$connection = mysqli_connect(host, username, password, database);

PDO

PDO is a more versatile extension that supports multiple database systems, including MySQL. It provides a consistent API for working with different databases and supports prepared statements, transactions, and more.

To use PDO, you need to replace your mysql_pconnect() function with a new PDO object. The syntax for creating a PDO object is as follows:

$connection = new PDO("mysql:host=host;dbname=database", username, password);

3. Updating your database connection code

Now that you have chosen either MySQLi or PDO, it's time to update your database connection code. In this step, we'll show you how to replace your existing mysql_pconnect() function with the appropriate alternative.

Using MySQLi

If you have chosen to use the MySQLi extension, your updated code will look like this:

// Replace your existing mysql_pconnect() function with the following code
$connection = mysqli_connect("localhost", "username", "password", "database");

// Check connection
if (!$connection) {
    die("Connection failed: " . mysqli_connect_error());
}

Using PDO

If you have chosen to use the PDO extension, your updated code will look like this:

// Replace your existing mysql_pconnect() function with the following code
try {
    $connection = new PDO("mysql:host=localhost;dbname=database", "username", "password");
    // Set the PDO error mode to exception
    $connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch(PDOException $e) {
    die("Connection failed: " . $e->getMessage());
}

4. Testing the updated code

After updating your database connection code, make sure to test your application to ensure that it works correctly without the mysql_pconnect() function. If any issues arise, double-check your code for syntax errors or misconfigurations.

FAQ

1. What are the main differences between MySQLi and PDO?

MySQLi is an extension specifically designed for working with MySQL databases, while PDO is a more versatile extension that supports multiple database systems, including MySQL. Both extensions offer improved performance and security compared to the deprecated mysql_pconnect() function.

2. How can I check my PHP version?

You can check your PHP version by running the following command in your terminal:

php -v

3. Why was the mysql_pconnect() function deprecated?

The mysql_pconnect() function was deprecated due to its lack of support for modern database features, such as prepared statements and transactions, as well as its poor performance and security compared to newer extensions like MySQLi and PDO.

4. Can I continue to use mysql_pconnect() in older PHP versions?

While you can continue to use mysql_pconnect() in PHP versions older than 5.5.0, it is highly recommended that you upgrade to a newer version of PHP and use MySQLi or PDO, as older PHP versions are no longer supported and may have security vulnerabilities.

5. How can I learn more about MySQLi and PDO?

To learn more about MySQLi and PDO, you can visit the official PHP documentation for MySQLi and PDO.

Related Links

• PHP: MySQL (Original) - Manual
• PHP: MySQLi - Manual
• PHP: PDO - Manual