Database Systems

3. This question refers to the following tables: Children, Playgroups Activities. The Children tables contains data about children (names, ages and addresses of parents) we assume for simplicity that names are unique, Playgroups says which child is in which playgroup and Activities says what children in the playgroup did on a certain date (for example, went to a zoo) Children Playgroups Name Age AddressPlaygroupID Name Activities PlaygroupID ADate Description Write SQL queries to do the following (a) Find a list of names of all children. (b) Find a list of names of all children aged 4 (1 marks) (2 marks) (c) Return a list of names and addresses of all children in the play- (3 marks) (d) Find a list of names and ages of children in a playgroup which group with PlaygroupID equal to 1 went to the zoo on the 21st of February 2009 (check for (5 marks) (e) Return a list of playgroup IDs and average age of children for (6 marks) (f) Find names and addresses of all children who are in the same (5 marks) (8) Add an extra column to the Activities table which is called Supervisor and has the type of values VARCHAR(20). (2 marks) (h) Replace description Zoo in the Activities table everywhere with (2 marks) Activities.Description value Zoo) each playgroup playgroup as a child called Amy Jones Visit to the Zoo