user: Question: What is the sum of the season with 8 clubs and Shanghai as the runners-up?
Columns: ['Season', 'Winners', 'Total wins', 'Runners-up', 'Third-place', 'Number of clubs']
Types: ['real', 'text', 'real', 'text', 'text', 'real']
Sample row: [1987.0, 'Liaoning', 1.0, 'Tianjin', 'Shanghai', 8.0]
SQL:

assistant: SELECT SUM("Season") FROM "Table" WHERE "Number of clubs" = 8.0 AND "Runners-up" = 'Shanghai';