The tuple relational calculus {SP(S)} is the set of all tuples such that P(S) is neither true nor false. such that P(S) is true. such that P(S) is false. such that S is s subset of P in S Given two relations R and S, which relational operator should be used to obtain a new relation consisting of the tuples that are in relation R but not in S ? Selection operator Division operator Join operator Difference operator Cartesian product operator What is the purpose of a Candidate Key in the definition of a relation? A Candidate Key represents the linkage between two relations A Candidate Key is an attribute which will distinguish each row in an index A Candidate Key is a potential primary key to uniquely identify each tuple in a relation A Candidate Key defines a subset of attributes in a relation A Candidate Key is used to identify relevant tuples in a query Question 4 2 pts An employee database is defined by the following relations: - employee = (employee_name, city, street) - works = (employee_name, company_name, salary) - company = (company_name, city) - manages = (employee_name, manage_name) What will the following expression return? Where , and are the is projection, AND and natural Join Operators respectively. A relation containing the name and employer of each employee who works for HSBC and who earns more than 20000 per annum A relation containing the name, street address and city of some employees who work for HSBC Bank and earn more than 20000 per annum. A relation containing full details of any employees who work for HSBC Bank and eam more than 20000 per annum. A relation containing the name, street address and city of all employees who work for HSBC Bank and earn more than 20000 per annum. A relation containing the name, street address and city of a number of employees who work for HSBC Bank and earn more than 20000 per annum. Given the relation Staff defined below Identify the reason the following SQL statement would be rejected during analysis. SELECT staff_no FROM Staff WHERE age >30; age is not a valid comparison predicate the query will return an empty set of tuples staff_no is not defined and type of comparison is incompatible staff_no is not defined in the relation all tuples have value of age greater than 30