We're given those two (relevant) relations:
Interest(SID, year, area, priority) A tuple represents an area that a student has declared an interest in for a particular year. The attribute priority indicates how strong the student’s interest in that area is, with 1 being the highest priority.
SApplication(SID, year, cgpa) A tuple in this relation indicates that a student applied to be mentored in a given year and had the given cgpa at the time.
SID - student id SID, year together make the primary key
Here's the question:
"Let’s say that a student is hard to match in a given year if they applied that year yet (a) they gave no interests that year or (b) they rated all their interests with the same priority that year. Write a query in relational algebra to find the SIDs of the students who have applied in at least one year and were hard to match in every year in which they applied."
I understand how part a can be done, but how can part b be done (in RA)?
