How to modify database configuration in php

PHP is a server-side scripting language widely used in web development. In the process of web development, we often need to connect to the database for data storage, query, update, delete and other operations. When connecting to the database, each project requires different configurations of the database, so we need to know how to modify the database configuration in PHP.

MySQL is one of the most commonly used relational databases, and the method of using MySQL in PHP is also very simple. Let's introduce how to modify the configuration of the MySQL database in PHP.

Step one: Open the PHP configuration file php.ini

To modify the MySQL configuration in PHP, you need to modify the php.ini file. The php.ini file is the PHP configuration file. Located in the PHP installation directory. Under Windows systems, it is usually in the C:\php\ directory, while under Linux systems, the php.ini file will be placed in the /usr/local/php5/lib/php.ini directory. Before modifying the configuration file, we need to back up the file to prevent modification errors.

In the php.ini file, we need to find the following two lines of code:

;extension=php_mysql.dll
;extension=php_mysqli.dll

These two lines of code starting with a semicolon indicate that the MySQL database extension is not enabled and the semicolon needs to be removed. To enable the MySQL extension, if it is PHP7 or above, there is only the following line:

;extension=mysqli

Here are the following instructions. If your local development environment does not have a database, please install and configure XAMPP at your own speed. Also remember that modifying php.ini requires restarting the web service.

Step 2: Modify MySQL configuration

When connecting to the MySQL database in PHP, we need to use some commonly used MySQL configuration parameters, such as database host name, database user name, database password, Database name, etc. These parameters can be modified in the php.ini file, for example:

mysql.default_host = localhost   # 修改主机名为localhost
mysql.default_user = root        # 修改用户名为root
mysql.default_password = abc123  # 修改密码为abc123
mysql.default_port = 3306        # 修改端口为3306
mysql.default_database = test    # 修改默认数据库为test

If you want to use the mysqli extension, you should modify the mysqli.default_host, mysqli.default_user, mysqli.default_password, mysqli.default_port and mysqli.default_socket parameters.

Note that the above configuration is just an example, and the content that needs to be modified will be different according to the actual situation.

Step 3: Restart the Web server

After completing the above two steps, you need to restart the Web server for the modification to take effect. Under Windows systems, you can stop the Apache server by clicking the "Stop" button on the XAMPP control panel, and then click the "Start" button to start the Apache server. Under Linux systems, you can restart the Apache server by executing the following command:

/etc/init.d/httpd restart

After starting the Web server, we can use the MySQL connection parameters in the PHP code to connect to the MySQL database. For example:

$conn = mysql_connect("localhost", "root", "abc123");
if (!$conn) {
   die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($conn);

PHP provides two extension libraries for connecting to MySQL, namely mysql and mysqli. Among them, mysql is an older extension library, while mysqli is a newer extension library that provides more functions. Therefore, it is recommended to use the mysqli extension library to connect to the MySQL database.

Summary

To modify the configuration of the MySQL database in PHP, you need to modify the php.ini file and restart the web server for the modification to take effect. When modifying, you need to pay attention to the settings of the MySQL connection parameters to ensure that the database can be connected correctly. At the same time, it is recommended to use the mysqli extension library to connect to the MySQL database for better performance and more functions.

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