I have 5 rows with ID: 1,2,3,4,5.
Then I made a query to try change those ID to: 2,3,4,5,6
Update table set `id` = `id` + 1
Duplicate entry '2' for key 'PRIMARY'.
Created a table num_sample with numbers from 1 to 100. Defined a primary key on the column num. And wrote this update
update num_sample set num = num + 1 order by num desc limit 100;
Worked absolutely fine in MySQL.