USE Personal 
SELECT 
    CONCAT( Surname,' ',LEFT(Firstname,1), '.', LEFT(Patronymic,1), '.') as ПІБ,
	Name_post as Посада,
    SizeSalary*Salary as Зарплата,
	DATEDIFF(yy,Birhtdate, '2020-12-31') as Вік_на_кінець_року,
	COUNT(CASE WHEN YEAR(GETDATE())-YEAR(Birhtdate) < 35 THEN 1 END) as Молодіж,
	COUNT(CASE WHEN YEAR(GETDATE())-YEAR(Birhtdate) > 35 AND YEAR(GETDATE())-YEAR(Birhtdate) < 60 THEN 1 END) as Зрілі,
	COUNT(CASE WHEN YEAR(GETDATE())-YEAR(Birhtdate) > 60 THEN 1 END) as Похилі
FROM Persona	p 
join Worker     w   on p.Id_man     = w.id_man 
join Post           on w.id_post    = Post.Id_post 
join Vacation   v   on p.Id_man     = v.id_man 
join Department d	on w.id_dep     = d.id_dep
WHERE main_work = 1 AND Education = 'вища'
Group by Surname, Firstname,Patronymic,Name_post,SizeSalary,Salary,Birhtdate