Doctrine Schema: float(18,4) ?

Use decimal instead of float in this situation:

    sale_price_eur:
      type: decimal(18)
      scale: 4

SQLSTATE[HY000]: General error: 1005 Can't create table

Let's see a very simple CORRECT relation and reasons why it can throw SQLSTATE[HY000]: General error...

relations:
    User:
      foreignAlias: Phonenumbers
      local: user_id
      foreign: id
      type: one
      foreignType: many

1. Did you forget to define the user_id field in the Phonenumber table?
2. Did you check the type of the user_id field and the Phonenumber table's id field? They must be exactly the same integer. If one of them is int(4) and the other is int(8), the building will fail.