Question 1 (18 marks, 3 marks each). For each of the following statements, represent it using CREATE TABLE statement. Note that there are both entity sets and relationship sets to be considered. 1. Patients attend doctors. You want to store the attending information and the date of attending. Patients identified by pid. Doctors is identified by did. 2. Continue 1, each patient attends doctors at most once. 3. Continue 2, each patient attends doctors at least once. 4. Continue 1, only existing doctors can be attended by a patient. 5. Continue 1, every doctor must be attended by a patient. 6. Continue 1, each of (Name, Address) and (Name, Age) uniquely identifies a patient.