Books are regularly issued by members on loan and returned after a period. Every book has title, author , publisher, year of publication, ISBN number (which is unique for the publication), and accession number (which is the unique number of the copy of the book in the library). There may be multiple copies of the same book in the library. Every student has name, roll number, department, gender, mobile number, date of birth, and degree. Every member has a maximum quota for the number of books he can issue for the maximum duration allowed to him. A book may be issued to a member if it is not already issued to someone else (trivial). Also, a book may not be issued to a member if another copy of the same book is already issued to the same member.