PHP Fatal error: Call to undefined function mysql_connect() in XXX.php

centos系统，安装好了apache和mysql数据库了之后，打开网站显示空白，然后进入/etc/httpd/logs查看日志文件，在error_log文件里面查看到以下错误：

[Thu Aug 10 10:40:43 2017] [error] [client 192.168.31.180] PHP Fatal error:  Call to undefined function mysql_connect() in /wwwroot/lyx_5ht6cv/web/inc/config.php on line 11

[Thu Aug 10 10:40:45 2017] [error] [client 192.168.31.180] PHP Fatal error:  Call to undefined function mysql_connect() in /wwwroot/lyx_5ht6cv/web/inc/config.php on line 11

[Thu Aug 10 10:40:45 2017] [error] [client 192.168.31.180] PHP Fatal error:  Call to undefined function mysql_connect() in /wwwroot/lyx_5ht6cv/web/inc/config.php on line 11

[Thu Aug 10 10:40:46 2017] [error] [client 192.168.31.180] PHP Fatal error:  Call to undefined function mysql_connect() in /wwwroot/lyx_5ht6cv/web/inc/config.php on line 11

[Thu Aug 10 10:40:53 2017] [error] [client 192.168.31.180] PHP Fatal error:  Call to undefined function mysql_connect() in /wwwroot/lyx_5ht6cv/web/1.php on line 10

[Thu Aug 10 10:40:56 2017] [error] [client 192.168.31.180] PHP Fatal error:  Call to undefined function mysql_connect() in /wwwroot/lyx_5ht6cv/web/1.php on line 10

[Thu Aug 10 10:40:56 2017] [error] [client 192.168.31.180] PHP Fatal error:  Call to undefined function mysql_connect() in /wwwroot/lyx_5ht6cv/web/1.php on line 10

然后运行phpinfo();,发现是没有安装有mysql组件，导致无法连接mysql数据库，使用yum安装一下mysql组件，一切恢复正常。

# yum install php-mysql

当然，您还可以一起安装其它的PHP组件.

#yum install php-mysql php-gd php-imap php-ldap php-odbc php-pear php-xml php-xmlrpc