Syntax:
ELT(N,str1,str2,str3,...)

Returns str1 if N = 1, str2 if N = 2, and so on. Returns NULL if N is
less than 1 or greater than the number of arguments. ELT() is the
complement of FIELD().

URL: http://dev.mysql.com/doc/refman/5.1/en/string-functions.html

