If multiple fields are specified in order by in the sql statement, how to sort?

For example: 
order by id desc, time desc is 

first sorted in descending order by id (priority) 
if some of the id fields are the same, then sorted in descending order by time (provided that the id is in descending order)

  order by name, age desc 

 If the name has the same priority

, it is sorted by age, and the third column is added

later , and the same is true, and so on.