Which committees have delegates from the democratic party?
select t1.committee from election as t1 join party as t2 on t1.party = t2.party_id where t2.party = "Democratic"
Which committees have delegates from the liberal party?
select t1.committee from election as t1 join party as t2 on t1.party = t2.party_id where t2.party = "Liberal"
Which committees have delegates from both parties, please?
select t1.committee from election as t1 join party as t2 on t1.party = t2.party_id where t2.party = "Democratic" intersect select t1.committee from election as t1 join party as t2 on t1.party = t2.party_id where t2.party = "Liberal"