EN
PostgreSQL - WHERE clause
0 points
In this article, we would like to show you how to use WHERE clause in PostgreSQL.
Quick solution:
xxxxxxxxxx1
SELECT "column1", "column2", ...2
FROM "table_name"3
WHERE condition;To show how the WHERE clause works, we will use the following table:
Note:
At the end of this article you can find database preparation SQL queries.
In this example, we will display information about every user whose salary is greater than 3000.
Query:
xxxxxxxxxx1
SELECT * FROM "users" WHERE "salary" > 3000;Output:
In this example, we will display information about every user whose name is John.
Query:
xxxxxxxxxx1
SELECT * FROM "users" WHERE "name" = 'John';Output:
Note:
PostgreSQL requires single quotes (
'') around text values.
create_tables.sql file:
xxxxxxxxxx1
CREATE TABLE "users" (2
"id" SERIAL,3
"name" VARCHAR(50) NOT NULL,4
"surname" VARCHAR(50) NOT NULL,5
"department_id" INTEGER,6
"salary" DECIMAL(15,2) NOT NULL,7
PRIMARY KEY ("id")8
);insert_data.sql file:
xxxxxxxxxx1
INSERT INTO "users"2
( "name", "surname", "department_id", "salary")3
VALUES4
('John', 'Stewart', 1, '3512.00'),5
('Chris', 'Brown', 2, '1344.00'),6
('Kate', 'Lewis', 3, '6574.00'),7
('Ailisa', 'Gomez', NULL, '6500.00'),8
('Gwendolyn', 'James', 2, '4200.00'),9
('Simon', 'Collins', 4, '3320.00'),10
('Taylor', 'Martin', 2, '1500.00'),11
('Andrew', 'Thompson', NULL, '2100.00');