CREATE TABLE Department (
  dept_id    INT          PRIMARY KEY,
  dept_name  VARCHAR(50) NOT NULL UNIQUE,
  location   VARCHAR(100)
);
CREATE TABLE Employee (
  emp_id     INT           PRIMARY KEY,
  emp_name   VARCHAR(100) NOT NULL,
  email      VARCHAR(150) UNIQUE,
  salary     DECIMAL(10,2) CHECK (salary > 0),
  dept_id    INT,
  hire_date  DATE          DEFAULT (CURRENT_DATE),
  FOREIGN KEY (dept_id) REFERENCES Department(dept_id)
    ON DELETE SET NULL ON UPDATE CASCADE
);
INSERT INTO Department VALUES
  (1, 'Engineering', 'Mumbai'),
  (2, 'HR',          'Pune'),
  (3, 'Finance',     'Delhi');
INSERT INTO Employee (emp_id, emp_name, email, salary, dept_id) VALUES
  (101, 'Aarav Shah',   'aarav@co.in',  75000, 1),
  (102, 'Priya Mehta',  'priya@co.in',  65000, 2),
  (103, 'Rohan Verma',  'rohan@co.in',  82000, 1),
  (104, 'Sneha Patil',  'sneha@co.in',  58000, 3),
  (105, 'Karan Joshi',  'karan@co.in',  91000, 1);
ALTER TABLE Employee ADD COLUMN phone VARCHAR(15);
ALTER TABLE Employee DROP COLUMN phone;
ALTER TABLE Employee RENAME TO Staff;
ALTER TABLE Staff RENAME TO Employee;
DELETE FROM Employee;

UPDATE Employee
SET    salary = salary * 1.10
WHERE  dept_id = 1;