6. Let the following database schema be given. Person(idnumber, name, dob, mother, father) primary key idnumber foreign key father references Person(idnumber) foreign key mother references Person(idnumber) Consider the following query: For the person with idnumber 42 produce a list of all their ancestors. Note that ancestors include grandparents, great-grandparents and so on. (a) Outline how you would solve this task programmatically, ad- dressing which particular SQL shortcoming you have to over- come. [5 marks] (b) What other kind of database might be more appropriate for the above query and why? [2 marks]