Vad sägs om detta?
SELECT @cnt := count(*) FROM my_table;
UPDATE my_table SET random = FLOOR(@cnt * RAND()) + 1;
Demo:http://sqlfiddle.com/#!2/a896d/4
Vad sägs om detta?
SELECT @cnt := count(*) FROM my_table;
UPDATE my_table SET random = FLOOR(@cnt * RAND()) + 1;
Demo:http://sqlfiddle.com/#!2/a896d/4