Published: June 2026•By Web Util Slyce Team•7 min read

SQL Queries — Common Examples & Patterns

A collection of practical SQL query examples for everyday database tasks. Format and beautify your SQL with our SQL Formatter.

CREATE TABLE

CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  name VARCHAR(100) NOT NULL,
  email VARCHAR(255) UNIQUE NOT NULL,
  role VARCHAR(20) DEFAULT 'user',
  created_at TIMESTAMP DEFAULT NOW()
);

SELECT Queries

Select All

SELECT * FROM users;

Select Specific Columns

SELECT id, name, email FROM users;

WHERE Clause

SELECT * FROM users WHERE role = 'admin';

LIKE Pattern Match

SELECT * FROM users WHERE email LIKE '%@example.com';

IN Operator

SELECT * FROM users WHERE role IN ('admin', 'moderator');

BETWEEN Range

SELECT * FROM orders WHERE total BETWEEN 100 AND 500;

ORDER BY

SELECT * FROM users ORDER BY created_at DESC;

LIMIT with OFFSET

SELECT * FROM users ORDER BY id LIMIT 10 OFFSET 20;

COUNT with GROUP BY

SELECT role, COUNT(*) FROM users GROUP BY role;

HAVING Filter

SELECT role, COUNT(*) FROM users GROUP BY role HAVING COUNT(*) > 5;

INSERT, UPDATE, DELETE

INSERT Single Row

INSERT INTO users (name, email, role) VALUES ('Jane Doe', 'jane@example.com', 'admin');

INSERT Multiple Rows

INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com'), ('Bob', 'bob@example.com');

INSERT ... RETURNING

INSERT INTO users (name, email) VALUES ('John', 'john@example.com') RETURNING id;

UPDATE All Matching

UPDATE users SET role = 'moderator' WHERE created_at < '2025-01-01';

UPDATE with Expression

UPDATE products SET price = price * 1.1 WHERE category = 'electronics';

DELETE Specific Rows

DELETE FROM users WHERE last_login IS NULL AND created_at < NOW() - INTERVAL '1 year';

DELETE All Rows (TRUNCATE)

TRUNCATE TABLE temp_logs;

JOIN Queries

INNER JOIN

SELECT u.name, o.total FROM users u INNER JOIN orders o ON u.id = o.user_id;

LEFT JOIN

SELECT u.name, o.total FROM users u LEFT JOIN orders o ON u.id = o.user_id;

Multiple Joins

SELECT u.name, o.id AS order_id, p.name AS product FROM users u JOIN orders o ON u.id = o.user_id JOIN order_items oi ON o.id = oi.order_id JOIN products p ON oi.product_id = p.id;

Aggregate Functions

Function	Example	Description
COUNT	COUNT(*), COUNT(DISTINCT col)	Counts the number of rows or non-null values
SUM	SUM(price * quantity)	Calculates the sum of values
AVG	AVG(rating)	Calculates the average value
MIN / MAX	MIN(price), MAX(price)	Returns the minimum or maximum value
COALESCE	COALESCE(phone, email, 'N/A')	Returns the first non-null value

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