4. What is the relation given by (5 Points) last. Certification(oNI): NURSEID and CI): CERTID(Salary250000 (NURSE) NURSE-CERT CERTIFICATION)) 5. Rewrite the relational Algebra from Question 4 using a Joins instead of a cross product. (5pts) 6 Draw the Query Tree for your answer in #5 (5pts) For the following do not assume any particular value for the data. Your answers should be able to accommodate any set of the data given by the structure at the beginning of this assignment. Write the relational Algebra to find Nurses (NID, Last Name and Department) that do not have any certifications (5 Pts) 7. 8. Write the expression to find how many Nurses for each department. We want the count and the department. eg. You may not know how the departments in advance. There could be more titles than are given above. (5pts) 9. Write the relational algebra expression to show the first, last and department for all nurses that have more than 2 certifications. (5 pts) 10. What constraints would the following code violate if any? (1pt each) First, Last, Department, Salary) a. INSERT INTO NURSE (NID, Ronald', 'Roe', 'ER', 54500) VALUES (NULL, b. DELETE FROM NURSE WHERE Last 'Baker. c. INSERT INTO CERTIFICATION (CID, Certification) VALUES (1, 'Ultrasound') d. INSERT INTO NURSE_CERT (CertlD, NurselD) VALUES (5, 2)