Data Types

What are Data Types?

Data types tell the database what kind of information you're storing. Just like you put clothes in a closet and food in a fridge - different data goes in different types.

The 4 Main Data Types

1. Numbers

INTEGER - Whole numbers (no decimals)

age INTEGER        -- 20, 25, 30
student_id INTEGER -- 1, 2, 3

DECIMAL - Numbers with decimals (for money!)

price DECIMAL(10,2)  -- 19.99, 100.50
salary DECIMAL(10,2) -- 50000.00

2. Text

VARCHAR(size) - Text with max length

name VARCHAR(100)   -- "John Smith"
email VARCHAR(200)  -- "john@email.com"

TEXT - Long text (no limit)

bio TEXT            -- Long description
content TEXT        -- Blog post

3. Date & Time

birth_date DATE           -- 2000-05-15
login_time TIME           -- 09:30:00
created_at TIMESTAMP      -- 2024-11-19 10:30:00

4. True/False

BOOLEAN - Yes or No values

is_active BOOLEAN    -- TRUE or FALSE
is_verified BOOLEAN  -- TRUE or FALSE

Quick Guide: Which Type to Use?

Storing ages, counts, IDs? → INTEGER

Storing money or prices? → DECIMAL(10,2)

Storing names, emails? → VARCHAR(100)

Storing long text? → TEXT

Storing dates? → DATE or TIMESTAMP

Storing yes/no? → BOOLEAN

Real Example

CREATE TABLE users (
  id INTEGER,
  name VARCHAR(100),
  email VARCHAR(200),
  age INTEGER,
  salary DECIMAL(10,2),
  is_active BOOLEAN,
  created_at TIMESTAMP
);

Tip: Always use DECIMAL for money (not FLOAT) - it's more accurate!

See Data Types in Action

name is VARCHAR (text), age is INTEGER (number), grade is CHAR (single letter)

SQL Editor

Output

Click "Run Query" to see results