Solution to unsuccessful connection to Mysql using localhost in PHP, localhostmysql

Solution to unsuccessful connection to Mysql using localhost in PHP, localhostmysql_PHP tutorial

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Release： 2016-07-13 10:20:30

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The solution to the unsuccessful connection to Mysql using localhost in PHP, localhostmysql

Problem found

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

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

Copy code The code is as follows:

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

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

Tips: 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 was in the process and restarted MySQL.

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

Directly use /usr/local/php5/bin/php /web/test.php to connect to the database
I also restarted apache, but it still doesn’t work

Doubtful point: Why the web page failed to execute but the command executed successfully

I feel depressed now. If I execute it directly using php command, it will succeed, but if I execute it through the web page, it will fail. Is it caused by apache? I searched a lot of information on the Internet but couldn't find a solution. The problem still persists after recompiling and installing apache.

Changed localhost to 127.0.0.1 successfully

After changing localhost to 127.0.0.1, the connection was successful. I started to fall into thinking dilemma: localhost failed but 127.0.0.1 succeeded?

ping localhost address is 127.0.0.1, yes

Open hosts and join

Copy code The code is as follows:

127.0.0.1 qttc

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

Different localhost connection methods cause

In order to understand the difference between the host filling in localhost and others when connecting to the database in PHP, I read a lot of information and finally learned:

When the host is filled in as localhost, mysql will use unix domain socket connection
When the host is filled in as 127.0.0.1, mysql will use tcp to connect
This is a feature of the Linux socket network. The win platform will not have this problem

Solution

Add
in the [mysql] section of my.cnf

Copy code The code is as follows:

protocol=tcp

Save and restart MySQL, the problem is solved!

php failed to connect to mysql. If it can be solved, additional 100 points will be added

Baidu HI me

Database password Correct?

$mysql=mysql_connect("localhost","username","password");
if($mysql){
echo "Database connection successful";
}else{
echo "failed";
}

php failed to connect to mysql

Is mysql support not enabled?
MySQL is no longer built-in support starting from php5. You need to set the php configuration file php.ini yourself to enable the mysql extension.