A file is organized so that the ordering of data records is the same as or close to the ordering of data entries in some index. Then that index is called

SELECT operation in SQL is equivalent to

Consider an Entity-Relationship (ER) model in which entity sets E₁ and E₂ are connected by an m : n relationship R₁₂. E₁ and E₃ are connected by a 1 : n (1 on the side of E₁ and n on the side of E₃) relationship R₁₃.

E₁ has two single-valued attributes a₁₁ and a₁₂ of which a₁₁ is the key attribute. E₂ has two single-valued attributes a₂₁ and a₂₂ of which a₂₁ is the key attribute. E₃ has two single-valued attributes a₃₁ and a₃₂ of which a₃₁ is the key attribute. The relationships do not have any attributes.

If a relational model is derived from the above ER model, then the minimum number of relations that would be generated if all the relations are in 3NF is _______.

Consider the following relation:

Student

Roll_No	Student_Name
1	Raj
2	Rohit
3	Raj

Performance

Roll_No	Course	Marks
1	Math	80
1	English	70
2	Math	75
3	English	80
2	Physics	65
3	Math	80

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___________.