It is very simple to create many virtualhost in apache. As following example
<VirtualHost *:80>
ServerName hr.example.com
ServerAlias hr.example.com
ServerAdmin admin@example.com
DocumentRoot /home/hr/public_html
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>
<VirtualHost *:80>
ServerName inventory.example.com
ServerAlias inventory.example.com
ServerAdmin admin@example.com
DocumentRoot /home/inventory/public_html
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>
<VirtualHost *:80>
ServerName hrd.example.com
ServerAlias hrd.example.com
ServerAdmin admin@example.com
DocumentRoot /home/hrd/public_html/public
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>
and filnally restart apache.