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PostgreSQL - WHERE clause

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In this article, we would like to show you how to use WHERE clause in PostgreSQL.

Quick solution:

SELECT "column1", "column2", ...
FROM "table_name"
WHERE condition;

Practical example

To show how the WHERE clause works, we will use the following table:

PostgreSQL - example data used with WHERE clause
PostgreSQL - example data used with WHERE clause

Note:

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

Example 1

In this example, we will display information about every user whose salary is greater than 3000.

Query:

SELECT * FROM "users" WHERE "salary" > 3000;

Output:

PostgreSQL - SELECT with WHERE clause result
PostgreSQL - SELECT with WHERE clause result

Example 2

In this example, we will display information about every user whose name is John.

Query:

SELECT * FROM "users" WHERE "name" = 'John';

Output:

PostgreSQL - SELECT with WHERE clause result
PostgreSQL - SELECT with WHERE clause result

Note:

PostgreSQL requires single quotes ('') around text values.

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');

PostgreSQL

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