What is Database Normalization and How Does it Improve Data Efficiency?

Plain English Explanation of Database Normalization

In the realm of database design, the concept of normalization plays a crucial role in structuring data efficiently to avoid duplication. Simply put, it's like creating a filing system that ensures you don't have multiple copies of the same document.

Understanding the Essence of Normalization

Imagine a table containing a list of employees and their countries of origin. Suppose every employee's row includes a lengthy country name, such as "Bosnia & Herzegovina." To avoid repetitive storage, normalization suggests creating a separate table for countries and assigning each country a unique identifier. Instead of storing "Bosnia & Herzegovina" 100 times, you simply store the number 45 (the country's identifier). This reduces data duplication and simplifies future changes.

Benefits of Normal Forms

Normalization is categorized into three forms:

• First Normal Form (1NF): Eliminates duplicate rows within a table.
• Second Normal Form (2NF): Prevents partial dependency, where non-key columns depend only on a part of the primary key.
• Third Normal Form (3NF): Removes transitive dependency, where non-key columns depend on other non-key columns.

Example of Normalization in Practice

Consider a scenario where we track employees' visited countries. Instead of storing the following table:

Person	CountryVisited	AnotherInformation	D.O.B.
Faruz	USA	Blah Blah	1/1/2000
Faruz	Canada	Blah Blah	1/1/2000

Applying 2NF, we create three tables:

• Table 1: List of Countries (ID, CountryName)
• Table 2: List of Persons (ID, PersonName, D.O.B.)
• Table 3: Employee-Country (PersonID, CountryID)

Now, if Faruz visits another country, only a single row is added to Table 3, connecting Faruz's ID to the new country ID. This normalized approach provides flexibility and eliminates data redundancy.

Remember, during a job interview, interviewers may assess your understanding of normalization by asking you to explain its principles and demonstrate its implementation in a given scenario.

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