Keys in Relational Schema
Understand the role and different types of keys in the relational model.
We'll cover the following...
Imagine trying to find a specific person in a massive city where no one has a unique address or SSN.
It would be chaos, right? In the world of databases, keys serve as unique identifiers, ensuring that we can pinpoint every piece of data accurately and reliably. They are the foundation that allows us to organize information, prevent errors, and connect related data across different tables.
By the end of this lesson, we’ll be able to:
Define and differentiate between various types of keys, including super, candidate, primary, composite, alternate, and foreign keys.
Understand the crucial role each key plays in maintaining data integrity and building relationships.
Confidently identify the different types of keys within a database schema.
Let’s dive in and unlock the power of keys!
Key
Before we explore the different types, let’s get a clear idea of what a key is. In a relational database, a key is an attribute (a column) or a set of attributes that uniquely identifies a tuple (a row) in a table. Keys are not just about uniqueness; they are fundamental to creating relationships between tables and ensuring the data we store is consistent and reliable. Without them, we would have no way to guarantee that each record is distinct or to link a customer to their orders, for example.
The hierarchy of keys
We’ll now explore the different types of keys, starting from the broadest concept and ...