test.js

const sequelize = new Sequelize('database', 'username', 'password', {
  dialect: 'mysql',
  host: "my.server.tld",
  port: 9821,
})

const Project = sequelize.define('project', {
  title: Sequelize.STRING,
  description: Sequelize.TEXT,
});

const Task = sequelize.define('task', {
  title: Sequelize.STRING,
  description: Sequelize.TEXT,
  deadline: Sequelize.DATE,
});

Project.hasMany(Task);
Task.belongsTo(Project);

await Project.create({
  title: 'todo list',
  description: 'the best todo manager ever',
});

const projectTodo = await Project.create({
  title: 'todo list',
  description: 'the best todo manager ever',
});

const task1 = await Task.create({
  title: 'foo',
  description: 'bar',
  deadline: new Date(),
  projectId: projectTodo.id,
});


const backofficeProject = await Project.findOne({
  where: { title: 'backoffice' },
});



const overdueProjects = await Project.findAll({
  include: [{
    model: Task,
    where: { deadline: { [Op.lt]: new Date() } },
    required: true, // → inner join
  }],
});