SQLite is the only one I know of that doesn’t enforce types by default, but I don’t know what the SQL spec requires.

No it is strongly typed, there is no accident that all PL extensions to the base query language have such a Ada/Pascal similarity.

Additional DML has plenty of options to enforce rules that keep data consistency.

While they make the life harder to delete/update/insert items in specific sequences, they can save the day on bad queries.

What happens if a query compares a string to a number?

You get a type error from the database.

As far as I can tell, some engines will implicitly coerce types so “7” = 7

But when do you get that type error?

This is the important bit.

You get it after the app is deployed, the query is ran and a result is expected.

When do I get a type error from my language if it's statically typed? That's right, before I even deploy.