SQ SQL

SELECT & WHERE

What you will learn

How to read data from a database table using SELECT and filter rows with WHERE.

Basic SELECT

SELECT * FROM users;

The star means "all columns". Always returns a table of results.

SELECT name, email FROM users;

Name only the columns you need — faster and clearer.

Filtering with WHERE

SELECT * FROM users WHERE age >= 18;

Operators: =, !=, <, >, <=, >=, LIKE, IN, BETWEEN.

SELECT name FROM users WHERE city = 'London' AND age > 21;

Combine conditions with AND, OR, NOT.

Common mistakes

  • Forgetting single quotes around string values: city = London (wrong), city = 'London' (right)
  • Using = instead of == for equality — SQL uses single =

Quick check below!

Next: JOINs