user: Question: Name the number of stage winners for Team Columbia
Columns: ['Stage (Winner)', 'General Classification', 'Points Classification', 'Mountains Classification', 'Young Rider Classification', 'Team Classification']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Stage 1 ( Mark Cavendish )', 'Mark Cavendish', 'Alexander Kristoff', 'Matt Wilson', 'Mark Cavendish', 'Topsport Vlaanderen']
SQL:

assistant: SELECT COUNT("Stage (Winner)") FROM "Table" WHERE "Team Classification" = 'Team Columbia';