Build Your Own Circular Log with MySQL(dt.deviantart.com)

  create table test_table( id integer identity(1), val varchar(max) )
  -----
  create trigger auto_updater on test_table after insert as
  begin
   declare @id integer = (select id from inserted)
   declare @val varchar = (select val from inserted)
   
   update test_table 
   set val=@val
   where id=@id%10+1
   
   if @id >= 10
      delete from test where id=@id
  end

  insert into test_table(val) values ('hooray')