SQL SELECT with WHERE Clause — Filtering Rows

Filtering Data with WHERE

The WHERE clause is how you filter rows returned by a SELECT statement. It supports comparison operators, pattern matching, set membership, and null checks.

Comparison Operators

SELECT * FROM employees
WHERE salary >= 50000
  AND salary < 100000;

Operator	Meaning
=	Equal to
<> or !=	Not equal to
<, >	Less than, greater than
<=, >=	Less/greater than or equal

Pattern Matching with LIKE

SELECT * FROM employees
WHERE name LIKE 'A%';      -- starts with A
WHERE email LIKE '%@gmail.com';  -- ends with @gmail.com
WHERE name LIKE '_a%';     -- second character is a

Set Membership with IN

SELECT * FROM employees
WHERE department_id IN (1, 3, 5);

Range with BETWEEN

SELECT * FROM orders
WHERE created_at BETWEEN '2025-01-01' AND '2025-12-31';

Null Checks

SELECT * FROM employees
WHERE manager_id IS NULL;       -- no manager assigned
WHERE phone IS NOT NULL;         -- has a phone number

Combining Conditions

Use AND, OR, and NOT to build complex filters. Parentheses control evaluation order:

SELECT * FROM employees
WHERE (department_id = 1 OR department_id = 3)
  AND salary > 60000
  AND name NOT LIKE 'Test%';