GATE | GATE CS 2019 | Question 61

A relational database contains two tables Student and Performance as shown below:

The primary key of the Student table is Roll_no. For the Performance table, the columns Roll_no. and Subject_code together from the primary key. Consider the SQL query given below:

SELECT S.Student_name, sum(P.Marks)
FROM Student S, Performance P
WHERE  P.Marks  >  84
GROUP BY S.Student_name;

The number of rows returned by the above SQL query is _________ .

Note: This was Numerical Type question.
(A) 5
(B) 4
(C) 3
(D) None of these.

Answer: (A)
Explanation: In where condition no condition over Roll_no so query produces all groups.

Student_name	Sum (P.marks)
Amit	452
Priya	452
Rohan	452
Smita	452
Vinit	452

Total 5 different student names all 5 group records in result. See: http://sqlfiddle.com/#!9/8a79d3/1/0
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