Why is this db_select not working?

Question

I can't seem to figure out, are you not allowed to chain db_select methods?

$nid = db_select("node", "n")
            ->fields("n", array("nid"))
            ->condition("f.entity_type", "node", "=")
            ->condition("f.deleted", 0, "=")
            ->condition("f.field_products_product_id", $entity->product_id, "=")
            ->addTag("node_access")
            ->join(
                "field_data_field_products",
                "f",
                "f.entity_id = n.nid"
            )
            ->execute();

I have the above, and it just won't work it keeps erroring on the join. Basically I want to do

SELECT nid FROM node JOIN field_data_field_products ON entity_id = nid WHERE ...

Answer 1

This is answered in this other question:

How to perform join with multiple columns using db_select?

Calls to SelectQuery::join() (like-wise SelectQuery::leftJoin(), SelectQuery::innerJoin(), and SelectQuery::addJoin()) chain-able because those methods don't return a SelectQuery object, but the actual alias used for the join.