VARCHAR first_significant_subdomain(VARCHAR url)
Extract the “first valid subdomain” from a URL and return it. If the URL is invalid, return an empty string.
mysql [(none)]>select first_significant_subdomain("www.baidu.com"); +----------------------------------------------+ | first_significant_subdomain('www.baidu.com') | +----------------------------------------------+ | baidu | +----------------------------------------------+ mysql [(none)]>select first_significant_subdomain("www.google.com.cn"); +--------------------------------------------------+ | first_significant_subdomain('www.google.com.cn') | +--------------------------------------------------+ | google | +-------------------------------------------------- mysql [(none)]>select first_significant_subdomain("wwwwwwww"); +-----------------------------------------+ | first_significant_subdomain('wwwwwwww') | +-----------------------------------------+ | | +-----------------------------------------+
FIRST_SIGNIFICANT_SUBDOMAIN