create сity_tb --"данные" города 
{
	name varchar(50), --название города
	x int, --координата X города
	y int  --координата Y города
}

create people_tb --данные человека
{
	x int, --координата X места жительства человека
	y int,--координата Y места жительства человека
	year int -- возраст
}

insert into сity_tb(name, x, y) values("Петрово", 10, 100);
insert into сity_tb(name, x, y) values("Васино", 20, 200);
insert into сity_tb(name, x, y) values("Борисов", 30, 300);

insert into people_tb(x, y, year) values(11, 101, 12);
insert into people_tb(x, y, year) values(11, 101, 13);
insert into people_tb(x, y, year) values(15, 101, 14);
insert into people_tb(x, y, year) values(11, 110, 12);

insert into people_tb(x, y, year) values(21, 198, 54);
insert into people_tb(x, y, year) values(19, 201, 57);
insert into people_tb(x, y, year) values(25, 198, 55);
insert into people_tb(x, y, year) values(21, 209, 54);

insert into people_tb(x, y, year) values(30, 300, 56);
insert into people_tb(x, y, year) values(31, 300, 56);
insert into people_tb(x, y, year) values(35, 300, 56);
insert into people_tb(x, y, year) values(30, 310, 56);

ON sqrt(power((сity_tb.x - people_tb.x), 2) + power((сity_tb.y - people_tb.y),2)) <= 5

select name, avg(year)
from сity_tb
left join people_tb on (сity_tb.x - people_tb.x)*(сity_tb.x - people_tb.x) + (сity_tb.y - people_tb.y)*(сity_tb.y - people_tb.y) < 25
group by name