SELECT: Retrieving Columns

SELECT is the entry point of every read query in SQL. It tells the database which columns you want to see in the result.

The sample dataset (customers, products, orders) is defined in the Introduction to SQL lesson.

Syntax

-- Select specific columns
SELECT column1, column2, column3
FROM table_name;

-- Select all columns
SELECT *
FROM table_name;

Examples

Example 1: Select all columns

SELECT *
FROM customers;

Result:

customer_id	name	email	city	country
1	Alice Johnson	alice@example.com	New York	USA
2	Bob Smith	bob@example.com	London	UK
3	Carol White	carol@example.com	Sydney	Australia
4	Dave Brown	dave@example.com	Toronto	Canada
5	Eve Davis	eve@example.com	New York	USA

Example 2: Select specific columns

Naming only the columns you need is the standard practice in real-world queries.

SELECT
    order_id,
    order_date,
    total_amount
FROM orders;

Result:

order_id	order_date	total_amount
1	2024-01-05	999.00
2	2024-01-10	59.98
3	2024-01-15	349.00
4	2024-02-01	796.00
5	2024-02-10	49.90
...	...	...

Common Mistake

Avoid SELECT * in production

SELECT * is useful for quick exploration but is risky in production code. If someone adds or renames a column, your query silently returns different data. Always list the columns you actually need.

Practice

Write a query that returns the name, category, and price of every product.

Show answer

SELECT
    name,
    category,
    price
FROM products;

Expected result:

name	category	price
Laptop	Electronics	999.00
Mouse	Electronics	29.99
Desk	Furniture	349.00
Chair	Furniture	199.00
Notebook	Stationery	4.99