Mysql in PHP - how to update only one row in table but with greatest id number

Question

I am trying to update fields in my DB, but got stuck with such a simple problem: I want to update just one row in the table with the biggest id number. I would do something like

Answer 1

Using PHP I tend to do run a mysqli_num_rows then put the result into a variable, then do an UPDATE statement saying where ID = the newly created variable. Some people have posted there is no need to use LIMIT 1 on the end however I like to do this as it doesn't cause any trivial delay but could prevent any unforeseen actions from being taken.

If you have only just inserted the row you can use PHP's mysqli_insert_id function to return this id automatically to you without needing to run the mysqli_num_rows query.