1.Получение информации о всех проектах, включая информацию об их руководителях:
SELECT projects.*, employees.Name_employee AS 'Руководитель'
FROM projects
INNER JOIN employees ON projects.Project_Head = employees.Name_employee;
SELECT employees.*
FROM employees
INNER JOIN `projects-employees` ON employees.id_employee = `projects-employees`.id_employee
WHERE `projects-employees`.id_project = 1;
SELECT projects.*
FROM projects
INNER JOIN `department-project` ON projects.id_project = `department-project`.Id_project
WHERE `department-project`.Id_department = 1;