user: Question: When volleyball has 2 bronze, what is the total number of silver?
Columns: ['Sport', 'Gold', 'Silver', 'Bronze', 'Total']
Types: ['text', 'real', 'real', 'real', 'real']
Sample row: ['Athletics', 0.0, 2.0, 2.0, 4.0]
SQL:

assistant: SELECT SUM("Silver") FROM "Table" WHERE "Bronze" = 2.0 AND "Sport" = 'volleyball';