How do I use the POSIX character classes upper and lower to search text in MySQL? I would like to search a body of text to find out when a specific word has been upper cased. MySQL has a REGEXP function with the POSIX character class [[:upper:]], but for the life of me I can't get it to return any results.

Say I want to search a column for the string literal 'FREE' only in upper case. 

Let's say the table structure is something like:

CREATE TABLE article_body (
id INT NOT NULL AUTO_INCREMENT,
article_id INT NOT NULL,
summary VARCHAR(255),
body_text TEXT,
PRIMARY KEY(id));


I want to find body_text columns where the word FREE is in all uppercase, e.g.

SELECT id, summary FROM article_body WHERE body_text REGEXP '[[:upper:]]+FREE';


But of course that syntax is invalid. 

Help?
From the article on mysql REGEXP:


  REGEXP is not case sensitive, except when used with binary strings.


A simple solution would be to use the BINARY operator:

SELECT * FROM article_body WHERE body_text REGEXP BINARY "FREE";


As to why your example doesn't work, the way I interpret it is "Any string with one or more uppercase letter followed by FREE", but of course FREE is case-insensitive there.