EN
PostgreSQL - search for NULL values in multiple columns
0
points
In this article, we would like to show you how to find rows with NULL
values in many columns in PostgreSQL.
Quick solution:
SELECT *
FROM "table_name"
WHERE "column1" IS NULL AND "column2" IS NULL AND "columnN" IS NULL;
SELECT *
FROM "users"
WHERE COALESCE("column1", "column2") IS NULL;
Practical example
To show how to find rows with NULL
values in many columns, we will use the following table:
Note:
At the end of this article you can find database preparation SQL queries.
Example 1
In this example, we will select all rows with NULL
value both in email
and department_id
column using IS NULL
and AND
keywords.
Query:
SELECT *
FROM "users"
WHERE "email" IS NULL AND "department_id" IS NULL;
Result:
Example 2
In this example, we will select all rows with NULL
value both in email
and department_id
column using COALESCE()
function.
Query:
SELECT *
FROM "users"
WHERE COALESCE("email", "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,
"email" VARCHAR(100),
"department_id" INTEGER,
"salary" DECIMAL(15,2) NOT NULL,
PRIMARY KEY ("id")
);
insert_data.sql
file:
INSERT INTO "users"
( "name", "surname", "email", "department_id", "salary")
VALUES
('John', 'Stewart', 'john@email.com', 1, '3512.00'),
('Chris', 'Brown', 'chris@email.com', 2, '1344.00'),
('Kate', 'Lewis', NULL, 3, '6574.00'),
('Ailisa', 'Gomez', 'ailisa@email.com', 2, '6500.00'),
('Gwendolyn', 'James', NULL, NULL, '4200.00'),
('Simon', 'Collins', NULL, 4, '3320.00'),
('Taylor', 'Martin', NULL, NULL, '1500.00'),
('Andrew', 'Thompson', 'andrew@email.com', NULL, '2100.00');