How to insert into a table the result of a select query with mikro-orm

I make a project with postgresql and I use mikro-orm to work with it.

There is a table of the following structure:

id | foreign_id | created_at
---+------------+-----------
 1 |          2 | 2023-05-29

It may contain multiple items with a single foreign_id. And I need to duplicate every row with foreign_id = 31, but with foreign_id = 42 and current date. I could write something like:

const entities = await entityRepo.findAll({ foreign_id: 31 });

for (const entity of entities) {
    const newEntity = entityRepo.create({ ...entity, foreign_id: 42, created_at: now() })
    entityRepo.persist(newEntity);
}

entityRepo.flush();

But it requires all the entities to be loaded into the memory of a nodejs app. In pure SQL, I could write something like this:

INSERT INTO my_table (id, foreign_id, created_at)
SELECT                id,         42, now()
FROM my_table
WHERE foreign_id = 31;

How to perform the same query with mikro-orm?

If you want the same query, then use the same query, there is no shame in using raw SQL for the parts that are not easily done with the ORM. You have the em.execute() for that. Or build it with knex, you have em.getKnex() for that.