Normalisasi Database

Unnormalized data example :

Student ID	Student Name	Date of Birth	Teacher	Subject
98765432	John Smith	2006-05-12	Mr. Smith	Mathematics
12345678	Emily Johnson	2007-09-21	Ms. Jones	Science
87654321	Michael Brown	2005-11-03	Mr. Brown	English
54321678	Sarah Lee	2006-08-17	Mrs. Lee	History
87654321	Michael Brown	2005-11-03	Mrs. Garcia	Geography
98765432	John Smith	2006-05-12	Mr. Johnson	Physics

• Rows with Student ID 87654321 and 98765432 are duplicates with different Teacher and Subject.

After Normalized

To normalize this table, we'll split it into multiple tables to eliminate redundancy and improve data integrity. We'll create separate tables for Students, Teachers, Subjects, and a table to manage the relationships between them.

Students Table:

Student ID	Student Name	Date of Birth
98765432	John Smith	2006-05-12
12345678	Emily Johnson	2007-09-21
87654321	Michael Brown	2005-11-03
54321678	Sarah Lee	2006-08-17

Teachers Table:

Teacher ID	Teacher Name
1	Mr. Smith
2	Ms. Jones
3	Mr. Brown
4	Mrs. Lee
5	Mrs. Garcia
6	Mr. Johnson

Subjects Table:

Subject ID	Subject
1	Mathematics
2	Science
3	English
4	History
5	Geography
6	Physics

Student-Teacher Relationship Table:

Student ID	Teacher ID
98765432	1
12345678	2
87654321	3
54321678	4
87654321	5
98765432	6

Student-Subject Relationship Table:

Student ID	Subject ID
98765432	1
12345678	2
87654321	3
54321678	4
87654321	5
98765432	6

In this normalized structure:

• Each table stores data about a specific entity (students, teachers, subjects).
• Relationships between entities are managed in separate tables (student-teacher and student-subject relationships).
• Redundancy is minimized, and data integrity is improved.