mysql_connect undefined

Hi,
Today I was unable to connect to mysql using mysql_connect function from php. I was able to use mysql database on command line, but not using mysql_connect function.

verified log files from

/etc/my.conf -> To Find where the mysql log files are stored
Mysql error log is store at /var/log/mysqld.log

Apache server log file.
/etc/httpd/conf/httpd.conf -> to find apache configuration file
Its log is store at /etc/httpd/logs/access_log or
Its log is store at /etc/httpd/logs/error_log

To install mysql with php use
yum install php-mysql