The SELECT Statement

SELECT is the single most important SQL keyword — it's how you ask a database to return data.

Selecting everything

The * wildcard means "all columns":

SELECT * FROM employees;

Selecting specific columns

In real applications you almost always want only the columns you need — it's faster and clearer:

SELECT first_name, last_name, salary
FROM employees;

Renaming columns with aliases

Use AS to give a column (or expression) a friendlier name in the results:

SELECT first_name AS "First Name", salary AS monthly_salary
FROM employees;

AS is optional in most engines — salary monthly_salary works too — but writing it explicitly makes queries easier to read.

Computed columns

You can select expressions, not just raw columns:

SELECT first_name, last_name, salary, salary * 12 AS annual_salary
FROM employees;

Removing duplicates with DISTINCT

DISTINCT returns only unique values:

SELECT DISTINCT job_title FROM employees;

Limiting how many rows come back

Every engine supports this, but the keyword differs:

Engine	Syntax
SQLite / PostgreSQL / MySQL	SELECT * FROM employees LIMIT 5;
SQL Server	SELECT TOP 5 * FROM employees;

Open the Code Playground, pick any SQL engine (SQLite, PostgreSQL, MySQL, or SQL Server), and paste these queries in directly — the practice database above is already loaded for you, every time.

-- A ready-to-query practice database is loaded automatically before every run —
-- no CREATE TABLE needed. Available tables:
--   departments  (id, name, location)
--   employees    (id, first_name, last_name, email, department_id, job_title, salary, hire_date, manager_id)
--   customers    (id, customer_name, city, country, signup_date)
--   products     (id, product_name, category, price, stock_quantity)
--   orders       (id, customer_id, employee_id, order_date, status)
--   order_items  (id, order_id, product_id, quantity, unit_price)

SELECT * FROM employees WHERE department_id = 1;