sorry that I did not reply to your question a month ago. in the meantime you surely found out what I meant. I post it anyway for others, who would like to know:
SELECT * does not work if you need one userdefined column like 'MD5(RAND()*NOW()) AS myrand', so you have to specify all the needed fields. 'AS myrand' creates an Alias for that column to be able to address it in the ORDER BY clause. the function rand() generates a number, multiplied by the timestamp value of the actual time. MD5 generates an 16bit-integer of this product. The resulting integer will be unique, so you can sort the result by 'myrand' and hopefully always get a different record as first and only record.
the ... were meant as the desired field names / conditions.