Answer 1: 1) Π ID, 2) Π ID, person_name (σcompany_name = “BigBank” (works)) person_name, city ( employee ⋈(σcompany_name = “BigBank” (works))) 3) Π ID,person_name, street, city (σcompany_name = “BigBank” ∧ salary > employee) 4) Π ID, person-name (employee⋈works⋈ company) 10000 ) ⋈ works ⋈ Answer 2: 1. Π ID, 2. Π ID, “BigBank”(works)) (σcompany_name =“BigBank”)(works)) person_name(employee) – Πperson_name person_name (σcompany_name ̸≠ Answer 3: ID name dept_name salary 22222 Almaty History 12212 Karina Biology 34452 Crick History 96000 180000 89000 Insert: (03659, Ayazhan, IT, 500000) It is error ,because department table does not have the IT department. Delete: (03659, Ayazhan, IT, 500000) Well delete (IT, Asan ,400000) from department . But , it would give an error cause instructor’s department referencing to the department with no ‘IT’. Answer 4: underline primary key employee (ID, person_name , street , city) works (ID , person_name , compamy_name ,salary) company (company_name, city)
