Consider the following functional dependencies in a database.
$$\eqalign{ & \,\,\,\,Date\,\,of\,\,Birth\,\, \to \,\,Age \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,Age\,\, \to \,\,Eligibility \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,Name\,\, \to \,\,Roll\_number \cr & \,\,\,\,\,Roll\_number\,\, \to \,\,Name \cr & Course\_number\, \to \,\,Course\_name \cr & Course\_number\, \to Instructor \cr & (Roll\_Number,\,Course\_number)\,\, \to \,\,Grade \cr} $$

The relation (Roll_number, Name, Date_of_Birth, Age) is

Consider the set of relations shown below and the SQL query that follows.

Students: (Roll_number, Name, Date_of_birth)
Courses: (Course number, Course_name, Instructor)
Grades: (Roll_number, Course_number, Grade)

Select distinct Name
From Students, Courses, Grades
Where Students.Roll_number = Grades.Roll_number
      and Courses.Instructor = 'Korth'
      and Courses.Course_number = Grades.Course_number
      and Grades.grade = 'A';

Which of the following sets is computed by the above query?

Consider the following SQL query:

Select distinct a1, a2, ..., an 

From r1, r2, ..., rm 

Where P; 

For an arbitrary predicate P, this query is equivalent to which of the following relational algebra expressions?

Which of the following scenarios may lead to an irrecoverable error in a database system?