1. Keys for Relational Data
Welcome to this adventure through data relationships and data normalization. In this video, we will focus on the foundational elements of relational data and the role of keys. We'll explore how these keys work and why they are essential for effective data management. Let's dive in!
2. Introduction to relational data
Here, we see an example of relational data. While it may seem like we have one large entity containing all our data points, we aim to simplify and structure this information. We will learn how to break down this large entity into smaller, more manageable entities.
One of the foundational elements of relational data is the keys that define and strengthen the relationships between different data entities. Think of these keys as the vital connectors in a network, much like roads that link various cities. By establishing keys, we will create clear connections between these individual pieces of data. We'll explore how primary and foreign keys help us to build these relationships effectively.
3. Introduction to relational data (1)
Keys, primary and foreign keys, are not just tools; they are the foundation for building our data model.
The concept of relational data refers to data neatly arranged into distinct entities. Keys, like primary and foreign keys, are what we use to link these entities together and define the relationships between different pieces of data.
4. The power of keys in relational data
Keys unlock the power of relational data with essential benefits. Let's review them.
Keys help us structure our data with related entities, safeguarding its integrity. Meaning our data is both well-organized and trustworthy.
Keys mirror real-world connections, offering a model that captures complex relationships and interactions.
They also make data access more efficient, enabling quick and precise data retrieval.
Finally, keys are critical for scalability, allowing our model to grow and adapt to business requirements changes while maintaining data integrity and reliability.
5. Recap of primary and foreign keys
Let's take a moment to recap. Remember primary keys? A primary key uniquely identifies each record in an entity.
In practice, when we create or replace a table, we first define the entity's name, list all the attributes and data types, and assign which one will be the primary key.
6. Recap of primary and foreign keys (1)
A foreign key, on the other hand, links one entity to another.
7. Recap of primary and foreign keys (2)
To add the foreign key, we need to adjust the script by adding the identifier column and the reference to the primary key of the foreign table.
8. Relationships in the data model
We've highlighted scalability as a key advantage of relational data. Let's manage the entry of new data into our model.
In our established physical data model, the products entity comprehensively details each item by its manufacturer.
9. Relationships in the data model (1)
Now that the business has informed us it will add product categories, we must adjust our model to accommodate this.
10. Adjusting the data model
Our next step is to first establish a new 'categories' entity with a unique primary key.
Then, we'll link it to our 'products' entity using a foreign key, capturing the one-to-many relationship where a single category can be associated with many products.
11. Adjusting the data model (1)
To incorporate the foreign key of categories into products, we'll use the ALTER TABLE command. This command modifies the entity's structure by adding a new column with ADD COLUMN, specifying the name and data type.
Then, we'll use ALTER TABLE again to add the foreign key using the familiar syntax of FOREIGN KEY and REFERENCES.
12. Adjusting the data model (2)
These alterations will complete the update to the physical data model of products.
13. Terminology and functions overview
Take some time to review the functions that we have learned so far.
14. Let's practice!
Now that you have learned that relational data would fit very well into the data model in Snowflake, let's practice.