title: MySQL: How do i update 50% of the rows, randomly selected?
body: <p>I want to update 50% of the rows in a table, randomly selected. Is there any way to do that?</p>
  
  <p>Edit: Just to clarify that it should always update 50% of the records, but of those 50% the rows must be randomly selected (not only the top 50% for instance). In other words, in avarage, every other record should be updated.</p>