Consider the following relations
Employee (E#, Ename, salary, Bdate, D#)
Department (D#, Dname, mgremp#, Location)
Dependent (E#, DependentName)
Which among these tuple calculus queries represent the following condition:
List the names of mangers who have at least one dependent.
- {m[Ename] | m ∈ EMPLOYEE ∧ ∃u, t (t ∈ DEPENDENT ∧ u ∈ DEPARTMENT ∧ t[E#] = u[mgremp#] ∧ m[E#] = u[mgremp#])}
- {e[Ename] | e ∈ EMPLOYEE ∧ ∃d (d ∈ DEPARTMENT ∧ d[Ename] = ‘manager’ ∧ e[D#] = d[D#])}
- {m[Ename] | m ∈ EMPLOYEE ∧ ∃u, t (t ∈ DEPENDENT ∧ u ∈ DEPARTMENT ∧ e[E#] = u[mgremp#] ∧ m[D#] = u[mgremp#])}
- {e[Ename] | m ∈ EMPLOYEE ∧ ∃u, t (t ∈ DEPENDENT ∧ u ∈ DEPARTMENT ∧ t[E#] = u[D#] ∧ m[E#] = u[D#])}