[Relational Algebra]
Write a relational algebra expression that will output first name and last name of computer science major male students who have borrowed books from "University of Iowa Main Library".
Relational Schema:
Book(ISBN:String, Title:String, Author:String, Category:String, Year:Integer)
Student(Student_Id:Integer, First_Name:String, Last_Name:String, Major:String, Gender:Char, DOB:Date)
Library(Library_Id:String, Library_Name:String, Library_City:String)
Book_Library(ISBN:String, Library_Id:String, Book_Id:Integer)
Borrow(Student_Id:Integer, Book_Id:Integer, Borrow_Date:Date, Return_Date:Date)
The schema above is a segment of a library database. It contains some basic information about books in different libraries and the students who borrow them.
In each relation, the key of the relation is underlined. The same book can be in many libraries. For example a network of libraries can have 5 copies of book "Tale of Two Cities". A library may also have several copies of the same book. ISBN is a unique ID assigned to a book. Book_Id is a unique ID assigned for a copy of the book by a specific library network.
The relation Book stores book ISBN, the book title, the author, the category it belongs to (e.g., Computer Science, Medicine) and year of publication.
The student table records the student's unique ID, the first name, the last name and some other information. The relation Library stores information about each of the libraries in a network of libraries.
Book_Library table records the books in a library with a unique ID for every copy of a book. The database keeps track of borrowing activity in relation Borrow. Date is of format "YYYYMMDD". If a book has not been returned than the "Return_Date" value will be NULL.