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PostgreSQL - CASE statement

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Created by:

Haris65

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In this article, we would like to show you how to use CASE statement in PostgreSQL.

Quick solution:

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CASE
    WHEN condition1 THEN result1
    WHEN condition2 THEN result2
    WHEN conditionN THEN resultN
    ELSE result
END;

Practical example

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To show how the CASE statement works, we will use the following table:

Note:

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

Example

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In this example, we will display information about users salary using CASE statement.

Query:

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SELECT "name", "salary",
CASE 
    WHEN "salary" > 6000 THEN 'Salary greater than 6000$'
    WHEN "salary" > 4000 THEN 'Salary greater than 4000$'
    WHEN "salary" >= 2000 THEN 'Salary greater than 2000$'
    ELSE 'Salary less than 2000$'
END AS "Salary information"
FROM "users";

Output:

Database preparation

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create_tables.sql file:

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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:

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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');