Is it possible to limit the number of records with a given key in mysql?

Question

MySQL

There is a table in the database that has a class column that can be repeated. How can I put a limit on the number of entries with the same class. I know that it is possible to create a trigger that, when inserted, will check the number of records with the selected class. But isn't there an easier way, something like ALTER TABLE MAX_ROWS?

Answer 1

Perhaps you have another column on which, together with the class column, you can hang a unique key. But in most cases, it is simply pre-checked with an additional request.