Understanding Databases and SQL: How It Works
This article is a complementary resource to the Learn SQL Basics course.
This article is a complementary resource to the Learn SQL Basics course.
A database is a collection of data organized and stored so that it's easy to access and use.
There are two main types of databases:
1. Non-Relational Database
2. Relational Database
Non-relational databases store data in flexible formats like key-value pairs, documents, or graphs. This means the data doesn't have to follow strict rules about how it's stored.
For example, in a non-relational database, you can store customer information in a container like this:
Key | Value |
---|---|
id | 1 |
name | John |
age | 25 |
If you have multiple data, they are stored as:
Non-relational databases are useful when data doesn't fit neatly into tables. However, they can be harder to work with when you need well-organized data.
Therefore, we prefer relational databases when structured data storage is required.
Relational databases store data in tables with rows and columns.
Example: Organizing Customers
If you're managing customers, you can organize them in a table as follows:
id | name | age |
---|---|---|
1 | John | 25 |
2 | Mary | 19 |
Here, data is neatly organized into rows and columns; this is how relational databases operate.
Since the data is stored in a tabular form, we can use SQL (Structured Query Language) to manage and interact with the data.
SQL is a tool for working with databases and helps you:
SQL is powerful and easy to learn, making it a versatile tool for professionals in Data Science, Web Development, and Business Intelligence.
The following key components work together to execute SQL queries:
1. Database
2. SQL Query
3. SQL Query Processing
A database is where data is stored and organized in a structured format.
We use SQL to store, manipulate, and retrieve data from the databases. The instructions we write for this are called SQL queries.
For example,
SELECT * FROM Customers;
When we execute an SQL query, the database engine processes it in three steps:
This approach ensures SQL queries are valid, flexible, and powerful.
1. Easy to Learn
SQL syntax is simple and intuitive.
For example, compare
SELECT CustomerName FROM Customers;
with plain English—"Select customer names from the customers' table."
2. Versatile Applications
SQL is used in a wide variety of fields like:
3. Universal Skill
SQL works with most database systems, handles large datasets, and remains a valuable skill across industries.