What are the names of parties that have both delegates on "Appropriations"?
SELECT T2.Party FROM election AS T1 JOIN party AS T2 ON T1.Party   =   T2.Party_ID WHERE T1.Committee   =   "Appropriations" INTERSECT SELECT T2.Party FROM election AS T1 JOIN party AS T2 ON T1.Party   =   T2.Party_ID WHERE T1.Committee   =   "Economic Matters"
parties that have both delegates on 'Appropriations' and another committee implies finding common parties between those on 'Appropriations' and those on another specified committee (though not mentioned in the requirement, the SQL code refers to 'Economic Matters'); INTERSECT is used to find common entries between two SELECT queries;