CREATE TABLE `employee`(
			`emp_id` INT PRIMARY KEY,
            `name` VARCHAR(20),
            `birth_date` DATE,
            `gender` VARCHAR(1),
            `salary` INT,
            `branch_id` INT, 
            `sup_id` INT
);

CREATE TABLE `branch`(
			`branch_id` INT PRIMARY KEY,
            `branch_name` VARCHAR(20),
            `manager_id` INT,
            FOREIGN KEY(`manager_id`) REFERENCES `employee`(`emp_id`) ON DELETE SET NULL
);

CREATE TABLE `client`(
			`client_id` INT PRIMARY KEY,
            `client_name` VARCHAR(20),
            `phone` VARCHAR(20)
);

CREATE TABLE `works_with`(
			`emp_id` INT,
            `client_id` INT,
            `total_sales` INT,
            PRIMARY KEY(`emp_id`, `client_id`),
            FOREIGN KEY(`emp_id`) REFERENCES `employee`(`emp_id`) ON DELETE CASCADE,
            FOREIGN KEY(`client_id`) REFERENCES `client`(`client_id`) ON DELETE CASCADE
);

ALTER TABLE `employee`
ADD FOREIGN KEY(`branch_id`)
REFERENCES `branch`(`branch_id`)
ON DELETE SET NULL;

ALTER TABLE `employee`
ADD FOREIGN KEY(`sup_id`)
REFERENCES `employee`(`emp_id`)
ON DELETE SET NULL;

DESCRIBE `employee`;
DESCRIBE `branch`;
DESCRIBE `client`;
DESCRIBE `works_with`;