What are the ids of enzymes that interact with at least one enzyme?
select distinct enzyme_id from medicine_enzyme_interaction
Give their names, too.
select t1.id, t1.name from enzyme as t1 join medicine_enzyme_interaction as t2 on t2.enzyme_id = t1.id group by t1.id
Which of those can interact as an 'activator'?
select t1.id, t1.name from enzyme as t1 join medicine_enzyme_interaction as t2 on t1.id = t2.enzyme_id where t2.interaction_type = 'activitor' group by t1.id
Which of those interacts as 'activator' with the most number of medicines?
select t1.id, t1.name from enzyme as t1 join medicine_enzyme_interaction as t2 on t1.id = t2.enzyme_id where t2.interaction_type = 'activitor' group by t1.id order by count(*) desc limit 1