SQL

Код к БД.sql

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+CREATE DATABASE office;
+
+DROP TABLE IF EXISTS devices;
+CREATE TABLE devices(
+	id_device INT PRIMARY KEY AUTO_INCREMENT,
+	deviceName VARCHAR(100) NOT NULL
+);
+
+INSERT INTO devices (deviceName) VALUES
+	('Принтер'),('Сканер'),('Комбайн');
+
+DROP TABLE IF EXISTS cabinets;
+CREATE TABLE cabinets(
+	id_cabinet INT PRIMARY KEY AUTO_INCREMENT,
+	cabinetNumber VARCHAR(100),
+	device_id INT, 
+	INDEX dev_ind (device_id),
+	FOREIGN KEY (device_id)
+		REFERENCES devices(id_device)
+		ON DELETE CASCADE
+);
+
+INSERT INTO cabinets(cabinetNumber,device_id) 
+VALUES('Кабинет 1',2),('Кабинет 2',3),('Кабинет 3',1);
+
+SELECT cabinetNumber, deviceName
+FROM devices INNER JOIN cabinets
+ON device_id = id_device
+ORDER BY id_cabinet;
+
+DROP TABLE IF EXISTS employers;
+CREATE TABLE employers (
+	id_employer INT PRIMARY KEY AUTO_INCREMENT,
+	employerName VARCHAR(100)
+);
+
+INSERT INTO employers (employerName) 
+VALUES ('Василий Петрович'),('Алексей Веселов'),('Максим Власов');
+
+DROP TABLE IF EXISTS employers_cab;
+CREATE TABLE employers_cab (
+	id INT PRIMARY KEY AUTO_INCREMENT,
+	employer_id INT,
+	cabinet_id INT,
+	INDEX emp_ind (employer_id),
+	INDEX cab_ind (cabinet_id),
+	FOREIGN KEY (employer_id)
+		REFERENCES employers(id_employer)
+		ON DELETE CASCADE,
+	FOREIGN KEY (cabinet_id)
+		REFERENCES cabinets(id_cabinet)
+		ON DELETE CASCADE
+);
+
+INSERT INTO employers_cab(employer_id, cabinet_id)
+VALUES (1,1), (1,3), (2,2), (2,3), (3,1), (3,2);
+
+SELECT cabinetNumber, GROUP_CONCAT(employerName) as Employers
+FROM employers_cab INNER JOIN (cabinets, employers)
+ON cabinet_id = id_cabinet AND employer_id = id_employer
+WHERE cabinet_id = 2;
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