Write the SQL query that can show which parties have candidates in all districts
There are 3 tables-parties, districts, candidates. table name: Parties Column name: party Conservative Green Liberal Libertarian Socialist table:Districts column names: district Essex Malton Riverdale Guelph Halton table: Candidates coloumn names : id, name, district, party 1 | Anne Jones | Essex | Liberal | 2 | Mary Smith | Malton | Liberal | 3 | Sara Black | Riverdale | Liberal | 4 | Paul Jones | Essex | Socialist | 5 | Ed White | Essex | Conservative | 6 | Jim Kelly | Malton | Liberal | 7 | Fred Price | Riverdale | Socialist | 8 | Bill Green | Guelph | Green | 9 | Garth Adams | Halton | Libertarian | 10 | Sam Adams | Guelph | Liberal | 11 | Jill Mackay | Halton | Liberal