MySQL 字符串分割 SUBSTRING_INDEX函数

SUBSTRING_INDEX(str,delim,count)

用delim 分割str，取第count个子串

url = 'http://www.medhelp.org/forums/Acne/show/56'

substring_index(url,"/",1)

结果是http:

substring_index(url,"/",2)

结果是http:/

substring_index(url,"/",3)

结果是http://www.medhelp.org

substring_index(url,"/",-1)

结果是56

substring_index(url,"/",-2)

结果是show/56


如何取中间的某个，比如取出 “show”这个单词？

substring_index(substring_index(url,"/",-2),"/",1)

取两次就行