PostgreSQL exercise

postgres/data.sql

@@ -0,0 +1,66 @@
+DROP TABLE IF EXISTS regions CASCADE;
+CREATE TABLE regions (
+  id serial PRIMARY KEY,
+  name varchar
+);
+
+INSERT INTO regions VALUES (1, 'Region 1');
+INSERT INTO regions VALUES (2, 'Region 2');
+
+DROP TABLE IF EXISTS locations CASCADE;
+CREATE TABLE locations (
+  id serial PRIMARY KEY,
+  address varchar,
+  region_id integer
+);
+
+INSERT INTO locations VALUES (1, 'Location 1 (Region 1)', 1);
+INSERT INTO locations VALUES (2, 'Location 2 (Region 1)', 1);
+INSERT INTO locations VALUES (3, 'Location 3 (Region 2)', 2);
+
+DROP TABLE IF EXISTS departments CASCADE;
+CREATE TABLE departments (
+  id serial PRIMARY KEY,
+  name varchar,
+  location_id integer,
+  manager_id integer
+);
+
+INSERT INTO departments VALUES (1, 'Department 1 (Location 1)', 1, 1);
+INSERT INTO departments VALUES (2, 'Department 2 (Location 1)', 1, 2);
+INSERT INTO departments VALUES (3, 'Department 3 (Location 2)', 2, 3);
+INSERT INTO departments VALUES (4, 'Department 4 (Location 3)', 3, 4);
+
+
+DROP TABLE IF EXISTS employees CASCADE;
+CREATE TABLE employees (
+  id serial PRIMARY KEY,
+  name varchar,
+  last_name varchar,
+  hire_date date,
+  salary integer,
+  email varchar,
+  manager_id integer,
+  department_id integer
+);
+
+INSERT INTO employees VALUES (1, 'Francesco', 'Rios', '2020-01-01', 5000, 'francesco.rios@dualbootpartners.com', NULL, 1);
+INSERT INTO employees VALUES (2, 'Maisha', 'Pratt', '2020-06-01', 4500, 'maisha.pratt@dualbootpartners.com', NULL, 1);
+INSERT INTO employees VALUES (3, 'Chad', 'Maldonado', '2021-01-01', 5000, 'chad.maldonado@dualbootpartners.com', NULL, 2);
+INSERT INTO employees VALUES (4, 'Wilson', 'Johns', '2021-01-01', 5000, 'wilson.johns@dualbootpartners.com', NULL, 3);
+INSERT INTO employees VALUES (5, 'Khalil', 'Christianson', '2022-01-01', 5000, 'khalil.christianson.@dualbootpartners.com', NULL, 4);
+INSERT INTO employees VALUES (6, 'Zaki', 'French', '2020-03-11', 4000, 'zaki.french@dualbootpartners.com', 1, 1);
+INSERT INTO employees VALUES (7, 'Sean', 'Terrell', '2021-05-21', 2000, 'sean.terrell@gmail.com', 1, 1);
+INSERT INTO employees VALUES (8, 'Karl', 'Higgins', CURRENT_DATE - 25, 1000, NULL, 2, 1);
+INSERT INTO employees VALUES (9, 'Ana', 'Velasquez', '2022-07-06', 2000, 'ana.velasquez@gmail.com', 3, 2);
+INSERT INTO employees VALUES (10, 'Daisie', 'Oconnor', '2022-06-13', 3000, 'daisie.oconnor@dualbootpartners.com', 3, 2);
+INSERT INTO employees VALUES (11, 'Keiran', 'Berg', '2022-05-08', 4000, 'keiran.berg@dualbootpartners.com', 4, 3);
+INSERT INTO employees VALUES (12, 'Jasmine', 'Walters', '2022-04-22', 5000, 'jasmine.walters@dualbootpartners.com', 4, 3);
+INSERT INTO employees VALUES (13, 'Callum', 'Gonzalez', '2022-03-24', 2000, 'callum.gonzalez@dualbootpartners.com', 5, 4);
+INSERT INTO employees VALUES (14, 'Travis', 'Ochoa', '2022-02-07', 3000, 'travis.ochoa@dualbootpartners.com', 5, 4);
+
+ALTER TABLE locations ADD FOREIGN KEY (region_id) REFERENCES regions(id);
+ALTER TABLE departments ADD FOREIGN KEY (location_id) REFERENCES locations(id);
+ALTER TABLE departments ADD FOREIGN KEY (manager_id) REFERENCES employees(id);
+ALTER TABLE employees ADD FOREIGN KEY (department_id) REFERENCES departments(id);
+ALTER TABLE employees ADD FOREIGN KEY (manager_id) REFERENCES employees(id);

postgres/queries.sql

@@ -0,0 +1,49 @@
+-- Показать работников у которых нет почты или почта не в корпоративном домене (домен dualbootpartners.com)
+SELECT
+  name, last_name, email
+FROM employees
+WHERE
+  email NOT LIKE '%@dualbootpartners.com'
+  OR email IS NULL;
+
+-- Получить список работников нанятых в последние 30 дней
+SELECT
+  name, last_name, email
+FROM employees
+WHERE
+  hire_date >= CURRENT_DATE - 30;
+
+-- Найти максимальную и минимальную зарплату по каждому департаменту
+SELECT
+  d.name,
+  MIN(e.salary) AS min_salary,
+  MAX(e.salary) AS max_salary
+FROM departments d
+JOIN employees e ON d.id = e.department_id
+GROUP BY d.id
+ORDER BY d.name;
+
+-- Посчитать количество работников в каждом регионе
+SELECT
+  r.name,
+  COUNT(*) AS employee_count
+FROM regions r
+JOIN locations l ON r.id = l.region_id
+JOIN departments d ON l.id = d.location_id
+JOIN employees e ON d.id = e.department_id
+GROUP BY r.id
+ORDER BY r.name;
+
+-- Показать сотрудников у которых фамилия длиннее 10 символов
+SELECT
+  name, last_name, email
+FROM employees
+WHERE
+  LENGTH(last_name) > 10;
+
+-- Показать сотрудников с зарплатой выше средней по всей компании
+SELECT
+  name, last_name, email, salary
+FROM employees
+WHERE
+  salary > (SELECT AVG(salary) FROM employees);