Normalization In Dbms

Normalization Step by Step

Unnormalized Table

student(roll, name, subjects, teacher, teacher_phone)
1, Aman, "Math,Science", Mr.Rao, 99999

1NF — Atomic Values

student(roll, name, subject, teacher, teacher_phone)
1, Aman, Math, Mr.Rao, 99999
1, Aman, Science, Ms.Sen, 88888

2NF — Remove Partial Dependency

Split so non-key columns depend on the whole key:

enrollment(roll, subject)
subject_info(subject, teacher, teacher_phone)

3NF — Remove Transitive Dependency

teacher_phone depends on teacher, not subject — separate it:

subject_info(subject, teacher)
teacher(teacher, teacher_phone)

Summary

• 1NF: atomic values. 2NF: no partial dependency. 3NF: no transitive dependency.
• Each step splits the table to remove a specific problem.

Normalization चरण-दर-चरण

Unnormalized Table

student(roll, name, subjects, teacher, teacher_phone)
1, Aman, "Math,Science", Mr.Rao, 99999

1NF — Atomic Values

student(roll, name, subject, teacher, teacher_phone)
1, Aman, Math, Mr.Rao, 99999
1, Aman, Science, Ms.Sen, 88888

2NF — Partial Dependency हटाएं

ऐसे split करें कि non-key columns पूरी key पर निर्भर हों:

enrollment(roll, subject)
subject_info(subject, teacher, teacher_phone)

3NF — Transitive Dependency हटाएं

teacher_phone, teacher पर निर्भर है, subject पर नहीं — अलग करें:

subject_info(subject, teacher)
teacher(teacher, teacher_phone)

सारांश

• 1NF: atomic values। 2NF: partial dependency नहीं। 3NF: transitive dependency नहीं।
• हर step एक specific समस्या हटाने के लिए table split करता है।