Solution to connection to Mysql using localhost in PHP

This article describes how to use localhost to connect to Mysql in PHP, but there is no problem when using 127.0.0.1, this article also explains the difference between using 127.0.0.1 and localhost to connect to the MySQL host. For more information, see Problems found

I encountered a problem yesterday when I was helping my colleagues compile and install the Linux environment:
The WEB server is apache and the database is MySQL.

So I wrote a PHP page to test the connection to the database:

The code is as follows:

$ Mysql = mysql_connect ('localhost', 'root ','');

Open http: // localhost/test. php to test

Tip: Can't connect to local MySQL server through socket...

Check that the environment is normal

I thought the database was not started, so I checked the process. MySQL restarted MySQL in the process.

Use mysql-u root-p to enter the MySQL operation interface

You can directly use/usr/local/php5/bin/php/web/test. php to connect to the database.
Apache is also restarted, which is also invalid.

Question: Why does the Web page fail to be executed but the command is successfully executed?

This is depressing. if you use the php command to directly execute the command, the execution will fail through the web page. Is it caused by apache? No solution was found after searching a bunch of materials on the Internet, and the problem of re-compiling and installing apache still persists.

Changed localhost to 127.0.0.1.

After I changed localhost to 127.0.0.1, the connection was successful and I began to think about the dilemma: Why did the localhost fail 127.0.0.1 but it succeeded?

The ping localhost address is 127.0.0.1.

Open hosts to join

The code is as follows:

127.0.0.1 qttc

When qttc is used, the host connection is normal, but localhost is not recognized.

Due to different localhost connection methods

To learn about the differences between localhost and other settings when using PHP to connect to the database, I read a lot of information and finally learned:

When the host is set to localhost, mysql uses unix domain socket connection.
Mysql uses tcp connection when the host is set to 127.0.0.1.
This is a feature of the linux socket network, and the win platform does not have this problem.

Solution

In the [mysql] section of my. cnf, add

The code is as follows:

Protocol = tcp

Save and restart MySQL. The problem is solved!