Column data types (INT, VARCHAR, DATE, DECIMAL) in SQL

Introduction

Column data types tell the database what kind of information each column will hold, like numbers, text, or dates. This helps keep data organized and accurate.

When creating a table to store customer information like names and birthdates.

When saving product prices that need decimal points for cents.

When recording dates for events or transactions.

When storing whole numbers like quantities or IDs.

Syntax

SQL

column_name DATA_TYPE(size)

DATA_TYPE defines what kind of data the column holds, like INT for whole numbers or VARCHAR for text.

Size is optional and usually used with VARCHAR to limit text length or DECIMAL to set precision and scale.

Examples

Stores whole numbers like age.

SQL

age INT

Stores text up to 50 characters long.

SQL

name VARCHAR(50)

Stores a date value like a birthday.

SQL

birthdate DATE

Stores numbers with up to 8 digits total and 2 digits after the decimal point, like money.

SQL

price DECIMAL(8,2)

Sample Program

This creates a Products table with different column types, adds two products, and then shows all the data.

SQL

CREATE TABLE Products (
  ProductID INT,
  ProductName VARCHAR(100),
  ReleaseDate DATE,
  Price DECIMAL(10,2)
);

INSERT INTO Products VALUES (1, 'Coffee Maker', '2023-05-10', 79.99);
INSERT INTO Products VALUES (2, 'Blender', '2022-11-20', 49.50);

SELECT * FROM Products;

Important Notes

INT is for whole numbers without decimals.

VARCHAR needs a size to limit how many characters it can hold.

DATE stores year-month-day format.

DECIMAL is great for exact numbers like money, where decimals matter.

Summary

Column data types define what kind of data each column holds.

Use INT for whole numbers, VARCHAR for text, DATE for dates, and DECIMAL for precise decimal numbers.

Choosing the right data type helps keep your data clean and useful.