Regular Expression MySQL

POSIX class             What the class matches
[:alnum:]               Alphabetic and numeric characters
[:alpha:]               Alphabetic characters
[:blank:]               Whitespace (space or tab characters)
[:cntrl:]               Control characters
[:digit:]               Digits
[:graph:]               Graphic (non-blank) characters
[:lower:]               Lowercase alphabetic characters
[:print:]               Graphic or space characters
[:punct:]               Punctuation characters
[:space:]               Space, tab, newline, carriage return
[:upper:]               Uppercase alphabetic characters
[:xdigit:]              Hexadecimal digits (0-9, a-f, A-F)