Summary
This chapter covers the categorization of SQL data types—numeric, character, date/time, and special—and explains how selecting the appropriate type for each column ensures data integrity and accurately represents real-world information.

General domain of usage
Database schema design

Understanding SQL data types is essential for designing databases that accurately represent real-world information. SQL data types are grouped into several main categories, each tailored for specific kinds of data you might need to store. The primary categories are: **numeric types**, **character types**, **date/time types**, and **special types**. 

- Numeric types handle numbers, such as a person's age or a product price. For example, you might store an employee's age as an `INTEGER`;
- Character types are used for text data, such as names or email addresses, and include types like `VARCHAR` for variable-length strings;
- Date/time types are designed for storing dates and times, such as a user's birthdate using the `DATE` type;
- Special types cover data that doesn't fit the other categories, such as `BOOLEAN` for true/false values that indicate whether a user is active.

To see how these categories work together, consider a table that tracks basic user information: age, name, birthdate, and whether the user is active.

```
CREATE TABLE user_overview (
    age INTEGER,
    name VARCHAR(50),
    birthdate DATE,
    is_active BOOLEAN
);
```

Each column in this table is chosen to match the kind of information it stores. The `age` column uses the numeric `INTEGER` type, perfect for whole numbers. The `name` column is a `VARCHAR`, a character type that can store varying lengths of text. The `birthdate` column is a `DATE` type, which is ideal for storing calendar dates. The `is_active` column uses the `BOOLEAN` special type, suited for true or false values.

These categories help you organize and validate your data efficiently. **Numeric types** ensure you only store numbers where appropriate, **character types** let you handle names and descriptions, **date/time types** keep track of important events, and **special types** like `BOOLEAN` allow you to represent logical states.



Which category would you use for storing a user's email address?

Which data type category is best for storing true/false values?

A beginner-friendly course that demystifies SQL data types, guiding you through their purpose, usage, and best practices. Learn how to choose the right data type for your data, avoid common pitfalls, and build robust, efficient databases.

Explore the foundational concepts of SQL data types, their categories, and why choosing the right type matters for your database.

Examine numeric and character data types in detail, including their properties, limitations, and best practices for selection.

Delve into the practical use of date/time and special data types, including their formats, functions, and unique behaviors.

Categories of SQL Data Types

Categories of SQL Data Types