ERD and Keys A hotel has many rooms.  A guest can make a reservation for one room or multiple rooms.  A reservation is associated with only one guest. Draw an ERD with the relationships and resolve any many to many relationships.  Create an ID for each entity you create (for example RoomID, GuestID, Reservation ID) as the Primary Key.  Identify any foreign keys in each entity where appropriate.

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A: Dear Student, The detailed answer to your question is given below -

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A: Please see the next step for answer.

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A: What is a unique key?

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A: Hey your task 4 query is correct as per provided in the pictures that you have solved.

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Enhanced ER Model

The enhanced ER model is an abbreviation for Enhanced Entity-Relationship (EER) model. As you know, the entity-relationship (ER) model is a pictorial illustration of the relationship between various entities of a domain. In the case of a large amount of data with multiple interrelated entities, the ER diagrams become complex and tough to interpret. For such cases, the need for enhancement in the ER model was observed, and thus, the EER model was designed.