You are hired to design database to keep track of the houses for real estate firms that are tracking house(s) for sale as well as customers who are looking to buy houses. Please consider following for your database design

     A house for sale can be listed with any firm. For house being "listed" with a firm means that the house owner has a contract with an agent who works for that firm. A house can only be listed by one agent and one firm.

  Each house on the market has price, address, owner, and a list of features. These features include the number of bedrooms, bathrooms, type of heating, appliances, size of garage, and similar things.

 The listing by a firm can be for different houses, and some features can be present in some houses but missing in others. 

 Each customer who is interested in buying a house has preferences for features (the number of bedrooms, bathrooms, etc.). Apart from these preferences, customers specify the price range of houses they are interested in buying. The firm keeps track of the contact information for the customers. 

Given these conditions, design an ER diagram for this application using Chen notation only (Chen notation). Write any unspecified assumptions that you need to make the specification complete. In your ER diagram;

 

a.     Identify each entity type and relationship type.

b.     Identify attributes and key attributes for each entity type and/or relationship type. You can always list additional attributes as per your needs.

c.      Identify Participate constraints and Cardinality Ratio.