PHP无法连接数据库的解决办法总结：

1、获取当前 mysql.default_socket、mysqli.default_socket、pdo_mysql.default_socket 配置信息

建立一个 PHP 文件，显示 phpinfo()，用浏览器打开如图:

在此页面，找到mysql.default_socket、mysqli.default_socket、pdo_mysql.default_socket信息

2、获取 MySQL socket 路径

通过控制台进入 MySQL, 输入命令: STATUS, 查找 UNIX socket 值#mysql -u root -p

Enter password:

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 8

Server version: 5.7.11 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.

mysql> STATUS

--------------

mysql Ver 14.14 Distrib 5.7.11, for osx10.9 (x86_64) using EditLine wrapper

Connection id: 8

Current database:

Current user: root@localhost

SSL: Not in use

Current pager: less

Using outfile: ‘‘

Using delimiter: ;

Server version: 5.7.11 MySQL Community Server (GPL)

Protocol version: 10

Connection: Localhost via UNIX socket

Server characterset: utf8

Db characterset: utf8

Client characterset: utf8

Conn. characterset: utf8

UNIX socket: /tmp/mysql.sock

Uptime: 8 days 15 hours 1 min 17 sec

Threads: 2 Questions: 21 Slow queries: 0 Opens: 114 Flush tables: 1 Open tables: 0 Queries per second avg: 0.000

--------------

3、这时候, 你对比 mysql.default_socket、mysqli.default_socket、pdo_mysql.default_socket 和 通过 MySQL UNIX socket 发现不一样, 这就是 mysql_connect(); 警告的原因: PHP 配置 mysql 有问题。

4、重新配置 PHP, 打开php.ini修改mysql.default_socket、mysqli.default_socket、pdo_mysql.default_socket 的值为: /tmp/mysql.sockpdo_mysql.default_socket=/tmp/mysql.sock

mysql.default_socket=/tmp/mysql.sock

mysqli.default_socket=/tmp/mysql.sock

或者修改my.cnf的socket：[client]

socket=/tmp/mysql.sock

[mysqld]

socket=/tmp/mysql.sock

5、重启nginx或者apache