How to join the `field_data_field_*` tables with `node` table using SQL?
Yes, you are right :)

In general, for each table from field_data_field_* family, if its entity_type is equal to  the "node" value, then it can be associated with the n.nid from the node table and if the entity_type is equal to the "user" then the entity_id value is associated with the uid value from the users table.

I hope it will help somebody.