4. (a) Describe how to enforce the entity integrity and the referential integrity. (b) (c) (4...

 

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4. (a) Describe how to enforce the entity integrity and the referential integrity. (b) (c) (4 marks) Describe how to check whether a relationship is a weak relationship or a strong relationship. (4 marks) Refer to the following description, draw the ER diagrams of the entities "Project", "Department", "Staff" and their relationships using Crow's Foot Model. For the relationship, please mark both the cardinality and the connectivity. You do not need to list the attributes of each entity, and do not need to mark the primary and foreign keys. Note that the ER diagram must be drawn in the form that can be directly implemented in the relation database. A company has several departments. Each staff belongs to one department. Each department has a manager, who is also a staff in this department. The company is running several projects. Each project has at least one leader and at least one member. Each staff participates in at least one project as the project member. Some staff also serves as the leader of the project. A staff can be the leader for at most one project at the same time. Each project is under the monitoring of a particular department. A department can monitor several projects, and some departments may not monitor any project. (12 marks) 4. (a) Describe how to enforce the entity integrity and the referential integrity. (b) (c) (4 marks) Describe how to check whether a relationship is a weak relationship or a strong relationship. (4 marks) Refer to the following description, draw the ER diagrams of the entities "Project", "Department", "Staff" and their relationships using Crow's Foot Model. For the relationship, please mark both the cardinality and the connectivity. You do not need to list the attributes of each entity, and do not need to mark the primary and foreign keys. Note that the ER diagram must be drawn in the form that can be directly implemented in the relation database. A company has several departments. Each staff belongs to one department. Each department has a manager, who is also a staff in this department. The company is running several projects. Each project has at least one leader and at least one member. Each staff participates in at least one project as the project member. Some staff also serves as the leader of the project. A staff can be the leader for at most one project at the same time. Each project is under the monitoring of a particular department. A department can monitor several projects, and some departments may not monitor any project. (12 marks)