In the world of database design, finding the candidate key is a crucial step. It determines the rest of the process, including normalization. In this article, we will discuss how to find the candidate key from a given set of functional dependencies.

Firstly, we need to understand that the attribute which cannot be determined must be present in the set of candidate key. To identify the candidate key correctly, we need to follow a few steps.

Let’s consider a set of functional dependencies: A -> CD, C -> D, A -> C, D -> B, and E -> F. From this set, we can say that A, B, C, and D are the candy attributes, which are not present on the right-hand side. However, E is not present on the left-hand side, which means it cannot determine any attribute.

Thus, the attribute which is not present in the right-hand side will be present in the candidate key. In this case, A and E are the candidate key attributes.

Next, we need to check if some other attributes are also required to form the set of candidate keys. To do this, we need to find the closure of these attributes. Closure is a set of attributes that can be determined from a given set.

In our example, we can determine all the attributes with the help of A. Therefore, our candidate key will be A, E, C, D, B, and F.

However, some examples may require taking other combinations apart from the attributes that are not present on the right-hand side. In such cases, we need to check all possible combinations that may act as a candidate key.

In conclusion, finding the candidate key is an essential step in database design. By following the steps mentioned above, we can identify the candidate key correctly.