Hi Guys, Many a times we have data required to be mapped in the collection framework. Like suppose if we talk about a simple example of student table where a student is having having fields such as students(sid, same, dateofbirth, qualification). Now if we want to have some more information to be stored about student such as the number of courses he/she has enrolled, the marks obtained in the different subjects, the reference email IDs so on and so forth, then, these information can't be stored in the single table and corresponding single fields can't also be able to handle all these information. Given the complexity of the situation we are going to separate these information in different tables such as courses, emails, marks, phones and references. The schema of all these tables would probably be as follows: students(sid, sname, dob, qualification); courses(sid, cname, idx); emails(sid, emailid, idx); marks(sid, marks); phones(sid, phoneno); refs(sid, rname,...