Let $$R=(A,B,C,D,E,F)$$ be a relation scheme with the following dependencies: $$C \to F,\,E \to A,\,EC \to D,\,A \to B.$$ Which of the following is a key for $$R?$$

Consider the schema $$R = \left( {S\,\,T\,\,U\,\,V} \right)$$ and the dependencies $$S \to T,\,\,T \to U,\,\,U \to V$$ and $$V \to S$$ let $$R =$$ $$(R1$$ and $$R2)$$ be a decomposition such that $$R1 \cap R2 \ne \phi .$$ The decomposition is:

Which of the following is/are correct?

Consider the set of relations

EMP (Employee-no, Dept-no, Employee-name, Salary)
DEPT (Dept-no, Dept-name, Location)

Write an SQL query to:

(a) Find all employee names who work in departments located at "Calcutta" and whose salary is greater than Rs.50,000.

(b) Calculate, for each department number, the number of employees with a salary greater than Rs.1,00,000.