First Normal Form (1NF) in DBMS Theory - Step-by-Step Execution

Concept Flow - First Normal Form (1NF)

Start with a Table

↓

Check for Atomic Values

Yes↓

No Repeating Groups?

Yes↓

Table is in 1NF

No↓

Remove Non-Atomic or Repeating Data

↓

Repeat Check

The flow checks if a table has only atomic values and no repeating groups. If yes, it is in 1NF; if not, it is fixed and rechecked.

Execution Sample

DBMS Theory

Table:
StudentID | Name | PhoneNumbers
1         | Ana  | 123, 456
2         | Bob  | 789

Check atomic values and repeating groups.

This table has a column with multiple phone numbers in one cell, violating 1NF.

Analysis Table

Step	Check	Condition	Result	Action
1	Check PhoneNumbers column	Contains multiple values in one cell?	Yes	Not atomic, violates 1NF
2	Check for repeating groups	Are there repeating groups?	Yes, PhoneNumbers	Violates 1NF
3	Transform table	Split PhoneNumbers into separate rows	Now atomic and no repeating groups	Table moves towards 1NF
4	Recheck PhoneNumbers	Are all values atomic now?	Yes	Table is in 1NF
5	End	All conditions met	Table conforms to 1NF	Stop

💡 Table has only atomic values and no repeating groups, so it is in 1NF.

State Tracker

Variable	Start	After Step 3	Final
PhoneNumbers	"123, 456", "789"	"123", "456", "789"	"123", "456", "789"
Table State	Has multi-valued cells	Split into atomic rows	All atomic, no repeats

Key Insights - 3 Insights

Why can't a column have multiple values like '123, 456' in one cell?

Because 1NF requires atomic values, meaning each cell must hold only one value. The execution_table step 1 shows this violation.

What does 'repeating groups' mean in a table?

Repeating groups are sets of multiple values stored in one column or multiple similar columns. Step 2 in execution_table identifies this issue.

How do we fix a table that violates 1NF due to repeating groups?

We split the multi-valued cells into separate rows or columns so each cell holds one atomic value, as shown in step 3.

Visual Quiz - 3 Questions

Look at the execution_table, what is the state of PhoneNumbers after step 3?

A PhoneNumbers still contain multiple values in one cell

B Each phone number is in its own row as atomic values

C PhoneNumbers column is removed

D PhoneNumbers are combined into one string

💡 Hint

Refer to execution_table row 3 and variable_tracker PhoneNumbers after Step 3

At which step does the table become compliant with 1NF?

A Step 4

B Step 3

C Step 1

D Step 5

💡 Hint

Check execution_table row 4 where all values are atomic and no repeats

If the PhoneNumbers column had only one number per cell from the start, how would the execution_table change?

A The table would never reach 1NF

B Step 3 would still split the numbers

C Step 1 would say 'No', skipping steps 2 and 3

D Step 5 would be removed

💡 Hint

Look at execution_table step 1 condition and action

Concept Snapshot

First Normal Form (1NF):
- Each table cell must hold only one atomic value.
- No repeating groups or arrays allowed in columns.
- Ensures data is organized in simplest form.
- Fix violations by splitting multi-valued cells into separate rows.
- 1NF is the foundation for higher normal forms.

Full Transcript

First Normal Form (1NF) means a database table must have only atomic values in each cell and no repeating groups. We start by checking if any column has multiple values in one cell, like a list of phone numbers. If yes, the table violates 1NF. We fix this by splitting those values into separate rows so each cell holds one value. After this, the table is in 1NF. This process ensures data is simple and organized, making it easier to manage and query.