MySQL Data Types

Every column in a table has a data type. It tells MySQL what kind of value the column can store, and how much space to use.

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Numeric types

Type	Use	Example
INT	Whole numbers (about -2 billion to 2 billion)	age INT
BIGINT	Very big whole numbers	views BIGINT
TINYINT	Small numbers (-128 to 127). TINYINT(1) is used as true/false	is_active TINYINT(1)
DECIMAL(p, s)	Exact decimals, like money. p = total digits, s = digits after the point	price DECIMAL(10,2)
FLOAT, DOUBLE	Approximate decimals	rating FLOAT

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String (text) types

Type	Use
CHAR(n)	Fixed length text, like a country code CHAR(2)
VARCHAR(n)	Text up to n characters. Most used for names and emails
TEXT	Long text, like a blog post or description
ENUM(...)	One value from a fixed list, like ENUM('male','female')
JSON	JSON data

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Date and time types

Type	Format	Example
DATE	YYYY-MM-DD	2025-01-15
TIME	HH:MM:SS	10:30:00
DATETIME	YYYY-MM-DD HH:MM:SS	2025-01-15 10:30:00
TIMESTAMP	Like DATETIME, stored as UTC and can update by itself	created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
YEAR	YYYY	2025

CREATE TABLE products (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(100) NOT NULL,
  price DECIMAL(10,2),
  description TEXT,
  in_stock TINYINT(1) DEFAULT 1,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

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How to choose

• Use DECIMAL for money, never FLOAT, because floats can give small errors.
• Use VARCHAR with a sensible limit, like 100 for a name and 255 for an email.
• Phone numbers are text (VARCHAR(15)), not numbers, because they can start with 0 or have a +.
• Store dates in a DATE or DATETIME column, not as text.

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Summary

• Pick the smallest type that fits your data.
• Numbers: INT, DECIMAL. Text: VARCHAR, TEXT. Dates: DATE, DATETIME.
• Next: CREATE DATABASE.

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