Even though database dependencies are common, they are known to confuse students and database professionals. Fortunately, they’re not as complicated as they seem – you just need to get used to working with them. Let’s learn more about database dependencies, why they’re important and the different dependency types to be aware of.
What are Database Dependencies and Why Do They Matter?
A database dependency is a constraint that defines the relationship between attributes. It happens when information stored in the same database table uniquely determines other information stored in the same table. It’s important to understand what database dependencies are because they provide the basic building blocks for database normalization.
Normalization is the process of efficiently organizing data in a database. There are two main objectives with database normalization. The first is to eliminate redundant data and the second is to ensure data dependencies make sense. By doing this, you can reduce the amount of space a database consumes and make sure the data is stored logically.
What are the Different Types of Database Dependencies?
Let’s explore some of the most common database dependency types so that you can get a better feel for how they work.
- Functional dependency. A functional dependency occurs when the information stored in a table can uniquely determine other information in the same table. Think of it as an association between two attributes of the same relation.
- Full functional dependency. A full functional dependency happens when you already meet the requirements for a functional dependency, and the set of attributes on the left side of the functional dependency statement can’t be further reduced.
- Trivial functional dependency. When you describe a functional dependency of an attribute on a collection of attributes that include the original attribute, it’s called a trivial functional dependency. It’s called “trivial” because it’s based on common sense.
- Transitive dependency. Transitive dependencies occur when there is an indirect relationship that causes a functional dependency.
- Multivalued dependency. When one or more rows in a table implies the presence of one or more other rows in the same table, it’s considered a multivalued dependency.
- Partial dependency. A partial dependency occurs when a non-prime attribute is functionally dependent on part of the candidate key.
Arkware is Experienced in Database Dependencies
Database dependencies can be difficult to understand. Thankfully, you are not left to your own devices. Arkware is a team of experienced database experts who can help you set up and maintain a powerful database. Contact us today to learn more about database dependencies and why they matter to your database.