Are you able for a user enter a code and it will search a database for a record with the code

I am building a web app like Google classroom. I was wandering if this feature is possible.

Yup! you definitely can

ok. can you know show me how to do it

Not sure how much you’ve used Adalo so far. But here’s the gist:

1- Create a list of those “records” or classes.
2- Put a search bar on the page
3- Filter the list by “custom filter” - Code of record - contains - search bar input

That way, as soon as the user types in a code, the list will shrink to only display the record with the code that the user typed in.