# Multivalued Dependency

## Multivalued Dependency

* Multivalued dependency occurs when two attributes in a table are independent of each other but, both depend on a third attribute.
* A multivalued dependency consists of at least two attributes that are dependent on a third attribute that's why it always requires at least three attributes.

**Example:** Suppose there is a bike manufacturer company which produces two colors(white and black) of each model every year.

| BIKE\_MODEL | MANUF\_YEAR | COLOR |
| ----------- | ----------- | ----- |
| M2011       | 2008        | White |
| M2001       | 2008        | Black |
| M3001       | 2013        | White |
| M3001       | 2013        | Black |
| M4006       | 2017        | White |
| M4006       | 2017        | Black |

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 as multivalued dependent on BIKE\_MODEL. The representation of these dependencies is shown below:

1. BIKE\_MODEL   →  →  MANUF\_YEAR &#x20;
2. BIKE\_MODEL   →  →  COLOR &#x20;

This can be read as "BIKE\_MODEL multidetermined MANUF\_YEAR" and "BIKE\_MODEL multidetermined COLOR".
