What drawbacks are there in scheduling an event to run every too often,say after every 60 seconds? I have this event i want to run every 60 seconds but i wonder if this will take up many resources in my database.

 CREATE EVENT myevent
    ON SCHEDULE EVERY 60 SECOND
    DO
       UPDATE yourdb.yourtable SET yourcolumn = RAND();


If make my event to run every too often,will it impact on the performance of my database?.
A server has very many events happening every minute.  Having an event that happens every 60 seconds is not automatically too frequent

If the event runs quickly and affects a small amount of data, then there should be no particular worry.  The bigger the impact of the event (CPU,I/O,memory,etc) the more cautious you need to be about scheduling.