First Normal Form (1NF) in DBMS Theory - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the First Normal Form (1NF) in database normalization?

1NF means that a table has only atomic (indivisible) values in each column and each record is unique. There should be no repeating groups or arrays.

beginner

Why is it important for a table to be in 1NF?

Being in 1NF helps avoid duplicate data and makes it easier to search, update, and maintain the database.

intermediate

Which of the following violates 1NF?<br>

StudentID | Courses
1         | Math, Science
2         | English

This violates 1NF because the 'Courses' column contains multiple values (Math, Science) instead of atomic values.

intermediate

How can you convert a table that violates 1NF into 1NF?

Split the multi-valued columns into separate rows so each cell contains only one value. For example, list each course in a separate row with the student ID.

beginner

Does 1NF require a primary key in the table?

Yes, 1NF requires that each row is unique, which means the table must have a primary key or a unique identifier.

What does 1NF ensure in a database table?

A Data is encrypted

B Each column contains atomic values only

C Table has no primary key

D Table has multiple repeating groups

1NF requires that each column contains atomic (indivisible) values only.

Which of these violates 1NF?

A A table with multiple phone numbers in one cell

B A table with unique rows

C A table with a primary key

D A table with single values in each cell

Multiple values in one cell violate 1NF because values must be atomic.

How can you fix a table that violates 1NF due to multi-valued columns?

A Remove the table

B Add more columns with multiple values

C Split multi-valued columns into separate rows

D Ignore the problem

Splitting multi-valued columns into separate rows ensures atomicity and fixes 1NF violation.

Does 1NF allow repeating groups in a table?

A No, never

B Yes, always

C Only if primary key exists

D Only for numeric data

1NF does not allow repeating groups; each field must contain only one value.

What is a key requirement for a table to be in 1NF?

A Data must be encrypted

B Columns can have multiple values

C No primary key needed

D Each row must be unique

Each row must be unique, usually ensured by a primary key, for 1NF compliance.

Explain what First Normal Form (1NF) means in database design and why it is important.

Think about how data should be stored in simple, indivisible pieces.

Describe how you would convert a table that has multiple values in one column into 1NF.

Consider splitting data to avoid lists inside a single cell.