user: Question: What is the sum of number with type 0-4-4 forney locomotive, number smaller than 20 and works number of 1251?
Columns: ['Number', 'Builder', 'Type', 'Date', 'Works number']
Types: ['real', 'text', 'text', 'real', 'real']
Sample row: [1.0, 'Hinkley Locomotive Works', '0-4-4 Forney locomotive', 1877.0, 1251.0]
SQL:

assistant: SELECT SUM("Date") FROM "Table" WHERE "Type" = '0-4-4 forney locomotive' AND "Number" < 20.0 AND "Works number" = 1251.0;