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-- Hint: use Ctrl+Enter for SQL autocomplete create table users( id int, name varchar(32), age int ); insert into users (id, name, age) values (1, 'Иван', 18),(2, 'Михаил', 18),(3, 'Светлана', 20),(4, 'Елена', 18); create table user_hobbies( user_id int, hobby varchar(32) ); insert into user_hobbies values (1, 'футбол'), (2, 'футбол'), (3, 'чтение'), (4, 'путешествия'); select age, hobby, count(*) popularity from user_hobbies join users on user_hobbies.user_id = users.id group by age, hobby; select distinct age, first_value(hobby) over (partition by age order by popularity desc) AS hobby from ( select age, hobby, count(*) popularity from user_hobbies join users on user_hobbies.user_id = users.id group by age, hobby ) hobbies ;