Извините, мой ответ был для SQL Server. Вот исправленная версия:
create table coach(id integer, name char(100));
insert into coach(id, name) values(1, 'Jack'), (2, 'Peter');
create table coach_career (coach_id integer, season_id integer, start date, end date);
insert into coach_career values (1, 95, '20170101', null), (2, 95, '20010101', null);
create table competition_seasons (id integer, name char(100));
insert into competition_seasons values (95, '2017/2018');
SELECT coach.*
FROM coach_career cc
LEFT JOIN coach ON coach.id = cc.coach_id
LEFT JOIN competition_seasons s ON s.id = cc.season_id
WHERE cc.season_id = 95
AND '2017/2018' like concat('%', cast(extract(year from cc.start) as char(100)), '%');