What Is Boyce-Codd Normal Form (BCNF)?

Boyce-Codd Normal Form (BCNF) is a database normalization form, and it's one of the more challenging ones to master. In a nutshell, BCNF means that your database tables are in this shape. Each table has a primary key and no non-trivial functional dependencies. That means there's no way to get an attribute value without looking at another attribute first. That's what "non-trivial" means—it's not just two attributes linked with an equals sign; it might be a whole chain of details that need to be looked at before you can get the value you want. A simple example would be if you were storing data about your friends' pets. If you had attributes like name, breed, color, and gender—all dependent on each other—your database would not be in BCNF because there are non-trivial functional dependencies among those four fields. Boyce-Codd Normal Form (BCNF) is one of the forms of database normalization. A database table is in BCNF if and only if there are no non-trivial functional dependencies of attributes on anything other than a superset of a candidate key. To understand what this means, let's look at an example. Say you have a database with two tables: one for customers and another for their purchases. In this example, the customer table has four columns: name, age, gender and location. The purchase table has three columns: product_id, quantity and price. If you were to create a table that combined these two tables into one, it would look something like this. CustomerID | Name | Age | Gender | Location | ProductID | Quantity | Price You can see an essential foreign relation between the customer table and the product table because they share a common field (ProductID). In addition to this critical foreign relationship between customer and product tables, there is also an attribute dependency between customer ID and ProductID because they are both used as part of the primary key for each table (CustomerID in Customer Table; ProductID in Product Table).