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;

Result: first 5 of 26 rows (the order can differ on other engines unless you add ORDER BY)

first_name	last_name	salary
Ali	Sheikh	188000
Sara	Qureshi	149000
Ahmed	Qureshi	101000
Ayesha	Sheikh	77000
Bilal	Ahmed	122000

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;

Result: first 5 of 26 rows (the order can differ on other engines unless you add ORDER BY)

first_name	last_name	salary	annual_salary
Ali	Sheikh	188000	2256000
Sara	Qureshi	149000	1788000
Ahmed	Qureshi	101000	1212000
Ayesha	Sheikh	77000	924000
Bilal	Ahmed	122000	1464000

Removing duplicates with DISTINCT

DISTINCT returns only unique values:

SELECT DISTINCT job_title FROM employees;

Result: first 12 of 15 rows (the order can differ on other engines unless you add ORDER BY)

job_title
Engineering Manager
Business Development Executive
SEO Specialist
HR Manager
Finance Manager
Support Team Lead
Financial Analyst
QA Engineer
Account Manager
Marketing Manager
HR Executive
Accountant

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.