Employees, dept and projects database

join_practice.sql

-- Create employees table
CREATE TABLE employees (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    department_id INT,
    salary DECIMAL(10, 2)
);

-- Create departments table
CREATE TABLE departments (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50) NOT NULL
);

-- Create projects table
CREATE TABLE projects (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(50) NOT NULL,
    manager_id INT
);

-- Insert data into departments
INSERT INTO departments (name)
VALUES
    ('HR'),
    ('Engineering'),
    ('Marketing');

-- Insert data into employees
INSERT INTO employees (name, department_id, salary)
VALUES
    ('Alice', 1, 55000),
    ('Bob', 2, 70000),
    ('Charlie', 2, 72000),
    ('Diana', NULL, 60000); -- No department assigned

-- Insert data into projects
INSERT INTO projects (name, manager_id)
VALUES
    ('Project A', 1),  -- Managed by Alice
    ('Project B', 2),  -- Managed by Bob
    ('Project C', NULL); -- No manager assigned