ISRO previous paper 2017 December, Computer Science question 13, set A

❔ Consider the following schema :

Sailors(sid,sname,rating,age)
Boats(bid,bname, colour)
Reserves(sid,bid,day)

Two boats can have the same name but the colour differentiates them.
The two relations

 ρ(Tempsids, (π_{sid, bid} Reserves) / (π_bid ( σ _{bname='Ganga'} Boats))),
π_sname(Tempsids ⋈ Sailors)

If / is division operation, the above set of relations represents the query
(a) Names of sailors who have reserved all boats called Ganga
(b) Names of sailors who have not reserved any Ganga boat
(c) Names of sailors who have reserved at least one Ganga boat
(d) Names of sailors who have reserved at most one Ganga boat

Answer is (a),

best refer to you tube video to understand the concept of division operation in DBMS.

Division Operator in DBMS Relational Algebra with Example in English, Hindi