PostgreSQL - AND, OR, NOT operators

In this article, we would like to show you how to use AND, OR and NOT operators in PostgreSQL.

To show how the mentioned operators work, we will use the following table:

Note:

At the end of this article you can find database preparation SQL queries.

AND

Syntax:

SELECT "column1", "column2", ...
FROM "table_name"
WHERE condition1 AND condition2 AND condition3 ...;

Practical example

In this example, we will display information about users with specified department_id AND salary greater than 1400$.

Query:

SELECT * FROM "users"
WHERE "department_id" = 2 AND "salary" > 1400;

Output:

OR

Syntax:

SELECT "column1", "column2", ...
FROM "table_name"
WHERE condition1 OR condition2 OR condition3 ...;

Practical example

In this example, we will display information about users whose name is Kate OR Simon.

Query:

SELECT * FROM "users"
WHERE "name" = 'Kate' OR "name" = 'Simon';

Output:

NOT

Syntax:

SELECT "column1", "column2", ...
FROM "table_name"
WHERE NOT condition;

Practical example

In this example, we will display information about users whose department_id is NOT 2.

Query:

SELECT * FROM "users"
WHERE NOT "department_id" = 2;

Output:

Database preparation

create_tables.sql file:

CREATE TABLE "users" (
	"id" SERIAL,
	"name" VARCHAR(50) NOT NULL,
	"surname" VARCHAR(50) NOT NULL,
	"department_id" INTEGER,
    "salary" DECIMAL(15,2) NOT NULL,
	PRIMARY KEY ("id")
);

insert_data.sql file:

INSERT INTO "users"
	( "name", "surname", "department_id", "salary")
VALUES
	('John', 'Stewart', 1, '3512.00'),
	('Chris', 'Brown', 2, '1344.00'),
	('Kate', 'Lewis', 3, '6574.00'),
	('Ailisa', 'Gomez', NULL, '6500.00'),
	('Gwendolyn', 'James', 2, '4200.00'),
	('Simon', 'Collins', 4, '3320.00'),
	('Taylor', 'Martin', 2, '1500.00'),
	('Andrew', 'Thompson', NULL, '2100.00');