GATE CS 2015 Set 1 Q27 — Tuple Calculus and SQL

Consider the following relation:

$$\overset{\text{Student}}{\begin{array}{|c|c|}\hline\\ \underline{\textbf{Roll\_No}}& \textbf{Student\_Name}\\ \hline 1& \text{Raj} \\ \hline 2& \text{Rohit}\\ \hline 3& \text{Raj} \\ \hline \end{array}} \qquad\overset{\text{Performance}}{\begin{array}{|c|l|r|c|}\hline\\ \underline{\textbf{Roll\_No}}& \underline{\textbf{Course}}& \textbf{Marks} \\ \hline 1& \text{Math}& 80 \\ \hline 1& \text{English}& 70 \\ \hline 2& \text{Math}& 75 \\ \hline 3& \text{English}& 80 \\ \hline 2& \text{Physics}& 65 \\ \hline 3& \text{Math}& 80 \\ \hline \end{array}}$$

Consider the following SQL query.

SELECT S.Student_Name, Sum(P. Marks) 
FROM Student S, Performance P
WHERE S.Roll_No= P.Roll_No
GROUP BY S.STUDENT_Name

The numbers of rows that will be returned by the SQL query is_________________.