Analyze and solve the problem that php5.4 cannot connect to mysql

PHP is a widely used programming language that plays an important role in web development. MySQL is a common relational database management system, often used together with PHP. However, in some cases, PHP will have problems connecting to the MySQL database, especially in PHP 5.4 version. So, how do we solve this problem?

First of all, we need to understand the cause of the problem. In PHP5.4 version, MySQL uses the MySQLi extension by default. This extension is an object-oriented extension and requires some additional configuration to work properly. If it is not configured correctly, it will fail to connect to MySQL.

Secondly, if we want to solve this problem, we need to configure it according to the following steps:

1. Modify the php.ini configuration file

In In the php.ini configuration file, we need to remove the comment symbol ";" before the following two lines of code:

extension_dir = "ext"
extension=php_mysqli.dll

These two The function of these codes is to reference the MySQLi extension library. After uncommenting them, you can enable the extension.

2. Enable PHP extension

We need to enable the mysqli extension in PHP so that PHP can use it. To enable this extension, you can follow these steps:

• Open the php.ini file.
• Find the following code:

;extension=php_mysqli.dll

• Change it to:

extension= php_mysqli.dll

• Save the file and restart the Apache server.

3. Check PHP version

The MySQLi extension requires PHP version 5.4 or above to work properly. Therefore, before enabling the MySQLi extension, we need to ensure that our PHP version is 5.4 or higher. If the version is too low, we must upgrade PHP to use the MySQLi extension.

4. Turn on the error prompt function of the MySQLi extension

If we encounter problems when using the MySQLi extension, we can turn on the error prompt function of the MySQLi extension to better understand Understand the problem. We can follow the steps below:

• Find the following code snippet in the php.ini file:

;error_reporting = E_ALL & ~E_DEPRECATED

• Modify it to:

error_reporting = E_ALL & ~E_DEPRECATED | E_WARNING

This modification allows error and warning information to be displayed in PHP, helping us to identify and analyze it more easily question.

Summary:

In PHP 5.4 version, since MySQL uses the MySQLi extension by default, we must correctly configure the extension to connect to the MySQL database normally. We can configure it according to the above four steps. When encountering a problem, we can also turn on the error prompt function of the MySQLi extension to better understand the problem. Of course, if we still can't solve the problem, we can also consider upgrading to a higher version of PHP.

Note: The above steps are only applicable to PHP installation under Windows operating system. Other operating systems may require different configurations.

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