Chapter 11: Problem 9

Illustrate how the process of creating first normal form relations may lead to mul. tivalued dependencies. How should the first normalization be done properly so that MVDs are avoided?

Short Answer

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The process of creating first normal form relations can lead to multi-valued dependencies, as multiple rows of data may be created for previously single-row values, leading to dependencies on a set of values. To avoid MVDs during the first normalization, separate the data into different tables based on a single theme, and link them together using a primary key.

Step by step solution

Understanding Database Normalization and First Normal Form

Database normalization is a process used to organize a database into tables and columns to reduce data redundancy and improve data integrity. The First Normal Form (1NF) is a level of database normalization where only scalar values are allowed. There are no set of values, repeating groups or arrays. A table is in 1NF if every cell contains a single value.

Understanding Multivalued Dependencies

A multivalued dependency (MVD) in a database is a type of functional dependency where an attribute in a relation depends upon another attribute in the same relation. In the case of a MVD, an attribute is dependent not just on a single value, but possibly set of values.

Illustrating 1NF Leading to MVDs

When converting a database to 1NF, you might create multiple rows of data to store values that were previously stored in a single row or column. These new tables can create Multivalued Dependencies. For example, consider a Student table where a student can have multiple hobbies and multiple languages. When converted to 1NF, this might lead to duplicate data for every combination of hobbies and languages, creating a MVD.

Avoiding MVDs during First Normalization

To avoid creating MVDs when you normalize to 1NF, separate the data into different tables based on a single theme. Using the previous example, instead of having a single Student table with both hobbies and languages, you can have a Student table, a Hobbies table, and a Languages table. Each of these tables would have a primary key (Student ID), that would link them together. By doing this, you avoid MVDs since each hobby or language aren't dependent on multiple students.

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Illustrate how the process of creating first normal form relations may lead to mul. tivalued dependencies. How should the first normalization be done properly so that MVDs are avoided?

Short Answer

Step by step solution

Understanding Database Normalization and First Normal Form

Understanding Multivalued Dependencies

Illustrating 1NF Leading to MVDs

Avoiding MVDs during First Normalization

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