AND / OR usage and examples

Overview

AND and OR combine predicates: AND requires every predicate to be TRUE, while OR requires at least one. AND has higher precedence, but production queries should use parentheses to show the intended business grouping instead of relying on remembered precedence. Comparisons involving NULL can also be UNKNOWN rather than simply true or false.

Basic syntax

SELECT * FROM orders WHERE department = 'Sales' AND amount > 1000;

Examples

AND / OR example

Filter orders to the Sales department with an amount above 1000, so both predicates must be satisfied.

Sample table

Table：orders

orders
id	customer_id	product_id	name	department	amount	status	created_at	discount
1	101	201	Alice	Sales	1200	paid	2026-01-03	0
2	102	202	Bob	IT	900	pending	2026-01-08	50
3	101	201	Cindy	Sales	1500	paid	2026-02-02	100
4	104	203	David	HR	700	cancelled	2026-02-15	0

Run result

result
id	customer_id	product_id	name	department	amount	status	created_at	discount
1	101	201	Alice	Sales	1200	paid	2026-01-03	0
3	101	201	Cindy	Sales	1500	paid	2026-02-02	100

Common issues

Are boundary values included?

Check the operator precisely: BETWEEN includes both ends, while adding or omitting equals changes a range.

How do I avoid mistakes with AND and OR?

Use parentheses to express business groups instead of relying on remembered precedence.

Why does a condition not match NULL?

NULL represents unknown, so a comparison may not be TRUE; use IS NULL or an explicit NULL strategy.

Keep reading

SELECT WHERE DISTINCT ORDER BY LIMIT LIKE BETWEEN OFFSET

AND / OR