VARCHAR cut_to_first_significant_subdomain(VARCHAR url)
Extract the part of the domain in the URL from the top-level subdomain down to the “first valid subdomain.” If invalid, return an empty string.
mysql [(none)]>select cut_to_first_significant_subdomain("www.baidu.com"); +-----------------------------------------------------+ | cut_to_first_significant_subdomain('www.baidu.com') | +-----------------------------------------------------+ | baidu.com | +-----------------------------------------------------+ mysql [(none)]>select cut_to_first_significant_subdomain("www.google.com.cn"); +---------------------------------------------------------+ | cut_to_first_significant_subdomain('www.google.com.cn') | +---------------------------------------------------------+ | google.com.cn | +---------------------------------------------------------+ mysql [(none)]>select cut_to_first_significant_subdomain("wwwwwwww"); +------------------------------------------------+ | cut_to_first_significant_subdomain('wwwwwwww') | +------------------------------------------------+ | | +------------------------------------------------+
CUT_TO_FIRST_SIGNIFICANT_SUBDOMAIN