How to solve the problem that MySQL cannot connect to PHP in CentOS7

When using the CentOS 7 operating system, we may encounter the problem that MySQL cannot connect to PHP. This is because CentOS 7 comes with a conflict between MariaDB and MySQL, resulting in the inability to connect to the database. This article will introduce you how to solve the problem that MySQL cannot connect to PHP in CentOS 7.

1. Disable MariaDB

1. In order to avoid conflicts with MariaDB, we need to disable it first. You can use the following command:

   systemctl stop mariadb.service #Stop the MariaDB service

   systemctl disable mariadb.service #Disable the MariaDB service

2. After disabling, We need to confirm that the MariaDB service has been stopped. You can use the following command:

   systemctl status mariadb.service # Check the MariaDB service status

   If the status is displayed as inactive, it means the Mariadb service has been stopped.

2. Install MySQL

1. Install MySQL dependencies:

   yum -y install wget

   yum -y install net-tools

2. Download the MySQL installation package:

   wget https://dev.mysql.com/get/mysql57-community-release-el7 -11.noarch.rpm

3. Install MySQL:

   rpm -ivh mysql57-community-release-el7-11.noarch.rpm

   yum install mysql-community-server

4. After the installation is complete, start MySQL:

   systemctl start mysqld

   systemctl enable mysqld

3. Modify MySQL configuration

1. Connect to MySQL:

   mysql -u root -p

   Enter password

2. Modify the MySQL configuration file:

   vim /etc/my.cnf

3. Add the following content under the [mysqld] configuration:

   skip-grant-tables

   Initialization password:

   use mysql;

   update user set authentication_string=password('password') where user='root';

   flush privileges;

   quit;

4. Modify skip-grant-tables in the configuration file to the following content:

   skip- grant-tables

   skip-character-set-client-handshake

5. Restart the MySQL service:

   Restart the MySQL service

   systemctl restart mysqld

4. Modify the PHP configuration file

1. Edit the PHP configuration file:

   vim /etc/php .ini

2. ##Search for mysql.default_socket or mysqli.default_socket and change it to the MySQL socket file address:
   mysql.default_socket = /var/lib/mysql/ mysql.sock
   mysqli.default_socket = /var/lib/mysql/mysql.sock
   pdo_mysql.default_socket = /var/lib/mysql/mysql.sock

Save changes and exit.

5. Test connection

1. Enter the following code in the terminal (the username and password need to be modified yourself):
   $con = mysqli_connect("localhost","username","password");
   if (!$con)
   {
   

   die('Could not connect: ' . mysqli_error());

   }

   echo 'Connected successfully' ;
   mysqli_close($con);
   ?>
   

Save the file to the root directory of Apache and access the file through the browser.

If Connected successfully is output, it means that the MySQL database can now be connected through PHP. If the test fails, please check the above steps and find the problem again.

Summary:

The above is the solution to the problem that MySQL cannot connect to PHP in CentOS 7. I hope it can provide help to students in need. If you have other questions, please leave a message to discuss.

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