Core Concept Mastery • DBMS Module
Let's look at a College Admissions process.
Primary Key (PK): Every student gets a unique ID Card (e.g., 101). No two students have the same number. This makes them unique. No one can exist in the college without an ID (Not Null).
Foreign Key (FK): When you join the "CSE Class", your name is written in the Class Register next to your ID Card Number (101). Why? If details are needed tomorrow, they check that number in the main office.
The number in the Class Register is the Foreign Key. It links back to your ID Card (PK). If you leave college (PK is gone), your name shouldn't be in the class register (Referential Integrity).
Without keys, data is just a messy pile of text. PKs stop duplicates (so we don't have two "John Smiths"), and FKs link tables together (so we know which student belongs to which class).
Your Student ID (PK) identifies you. When you enroll in a course, the Course List writes down your Student ID (FK) to link you to that class.
Start by identifying the keys in both tables.
"A key that creates a relationship between two tables is called?"
Foreign Key.