I have 3 types of users in my system. each type has different information I created the following tables:

BaseUser(base_user_id, username, password, additional common data)

base_user_id is PK and Identity

UserType1(user_id, data related to type1 only)

user_id is PK and FK to base_user_id

UserType2(user_id, data related to type2 only)

user_id is PK and FK to base_user_id

UserType3(user_id, data related to type3 only)

user_id is PK and FK to base_user_id

Now I have relation from each type of user to warehouses table. Users from type1 and type2 should have only warehouse_id and users from type3 should have warehouse_id and customer_id.

I thought about this structure:

WarehouseOfUser(base_user_id,warehouse_id)

base_user_id is FK to base_user_id in BaseUser

WarehouseOfTyp3User(base_user_id,warehouse_id, customer_id)

base_user_id is FK to base_user_id in BaseUser

The problem is that such structure allows 2 things I want to prevent: 1. add to WarehouseOfTyp3User data of user from type2 or type1. 2. add to WarehouseOfUser data of user from type3.

what is the best structure for such case?