What Is Multivalued Dependency?

Are you curious to know what is multivalued dependency? You have come to the right place as I am going to tell you everything about multivalued dependency in a very simple explanation. Without further discussion let’s begin to know what is multivalued dependency?

What Is Multivalued Dependency?

Multivalued dependency is a concept in database theory that describes the relationship between attributes in a relation. In a database, a relation is a table with rows and columns, where each column represents an attribute and each row represents a record. Multivalued dependency is a constraint that ensures that certain attributes in a relation are functionally dependent on other attributes.

Definition Of Multivalued Dependency

In a relation, a multivalued dependency occurs when two or more attributes are functionally dependent on a third attribute, but not on each other. In other words, the values of one attribute determine the possible values of another attribute, but those values are not dependent on each other. This is often represented by an arrow pointing from one attribute to another.

For example, consider a relation that contains information about books and authors. In this relation, the attributes are book_id, author_id, author_name, and book_title. A multivalued dependency occurs when multiple authors can write the same book, but the authors themselves are not dependent on each other. In this case, the author_name attribute is functionally dependent on the book_id attribute, but not on the author_id attribute.

Types Of Multivalued Dependency

There are several types of multivalued dependency, including:

Nontrivial Multivalued Dependency: A nontrivial multivalued dependency exists when there are at least three attributes in a relation, and two or more of those attributes are independent of each other.
Trivial Multivalued Dependency: A trivial multivalued dependency exists when there are only two attributes in a relation, or when all the attributes in a relation are dependent on each other.
Join Dependency: A Join dependency exists when a relationship can be divided into two or smaller relations, and the original relation can be reconstructed by joining these smaller relations.

Uses Of Multivalued Dependency

Multivalued dependency is an important concept in database theory because it helps to ensure that relations are in a normal form. Normalization is the process of organizing data in a database to minimize redundancy and improve efficiency. Multivalued dependency helps to identify relations that are not in a normal form and to correct them by breaking them down into smaller, more efficient relations.

Conclusion

Multivalued dependency is a fundamental concept in database theory that describes the relationship between attributes in a relation. It is important for ensuring that relations are in a normal form and for optimizing the efficiency of a database. By understanding multivalued dependency, database designers and administrators can create more efficient and effective databases that meet the needs of their users.

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FAQ

What Is Meant By Multivalued Dependency?

The concept of MVD or Multivalued dependency refers to having multiple rows in a given table. Thus, it implies that there is a presence of multiple other rows in the very same table.

What Is An Example Of A Multivalued Dependency?

Example: Suppose there is a bike manufacturer company that produces two colors(white and black) of each model every year. Here columns COLOR and MANUF_YEAR are dependent on BIKE_MODEL and independent of each other. In this case, these two columns can be called multivalued dependent on BIKE_MODEL.

What Is Multivalued Dependency And How It Can Be Removed?

The 4th Normal Form can cause Multivalued Dependencies. If a relation is in Boyce codee Normal form, it has to remove the multivalued Dependencies. Explanation − The multivalued dependencies are that, if there is a dependency or relation in a table, then one value has multiple dependencies occur.

What Are Multivalued Dependency And 4nf In Dbms?

4NF in DBMS stands for Fourth Normal Form and the relation is said to be in 4NF if the relation is in Boyce Codd Normal Form and has no multi-valued dependency. Multi-valued dependency for a relation A −> B exists when for a single value of A, multiple values of B exist.

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