题解 | #用户名规范化#
用户名规范化
https://www.nowcoder.com/practice/fcf0413ca8164324a91e7e2f4421f369
原来substr省略最后一位就表示截取到最后，我还写了一大堆，又跟大佬们学到了东西～～～
select device_id,concat(upper(substr(substring_index(blog_url,'/',-1),1,1)), lower(substr(substring_index(blog_url,'/',-1),2, char_length(substring_index(blog_url,'/',-1))))) as user_name from user_submit order by device_id desc