MySQL Regexp无法正常工作

Question

I have the following query:

SELECT  `admin_users`.* 
FROM `admin_users` 
WHERE (avatar REGEXP 'avatars/Name-[0-9]+.jpg+')  
ORDER BY `admin_users`.`avatar` 
DESC LIMIT 1

It's ok if I have something like:

• avatars/Name-5.jpg
• avatars/Name-6.jpg

But if I have, avatars/Name-15.jpg , for example, it doesn't return in query.

In other words, It only works for 1 digit, not for more. How can I solve it?

Answer 1

When comparing strings (an that is what avatar is), "avatars/Name-1..." comes before "avatars/Name-5..." simply because the string "1" comes before "5".

It is not practical to order those by an embedded number. This would do what you want, but it is pretty cryptic:

ORDER BY 0 + MID(avatar, 14)

To explain

1. MID will start at the 14th character of 'avatars/Name-15.jpg' and extract '15.jpg'.
2. 0+ will take that string, convert it to a number and deliver the number 15. (When a string is turned into a number, the first characters are taken as long as it looks like a number. So, 0+'abc' will deliver 0 , since there is nothing at the beginning of abc that looks like a number.)

If the left part were not exactly 14 characters in all cases, the trick will fail. And it may get so complicated as to be 'impossible' in SQL.