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PostgreSQL - count rows with NULL values
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In this article, we would like to show you how to count rows with NULL values in PostgreSQL.
Quick solution:
SELECT COUNT(*) AS "alias_name"
FROM "table_name"
WHERE "column_name" IS NULL;
Practical example
To show you how to count rows with NULL values, we will use the following users table:
Note:
At the end of this article you can find database preparation SQL queries.
Example
In this example, we will count the number of rows with NULL values in department_id column.
Query
SELECT COUNT(*) AS "NULL_values_in_column"
FROM "users"
WHERE "department_id" IS NULL;
Result:
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, '6000'),
('Chris', 'Brown', 2, '6000'),
('Kate', 'Lewis', 3, '4000'),
('Ailisa', 'Gomez', NULL, '4000'),
('Gwendolyn', 'James', NULL, '4000'),
('Simon', 'Collins', 4, '4000'),
('Taylor', 'Martin', 2, '2000'),
('Andrew', 'Thompson', NULL, '2000');