减少mysql中的整列

I have my "Id" column that looks like this:

Id
----
1
2
3
4
...
59
60

How do i decrease each one of them so that "Id" 20 for example will be 19 and 41 will be 40? (And so on) Is there a mysql command for that?

UPDATE mytable SET id = id - 1

like this

update YourTable
set id = id - 1