Table: volker_race_data
Columns: year
class
team
chassis
tyre
laps

Question: What's the total of Year that's got a Team of Porsche Kremer Racing?
SQL: SELECT SUM("year") FROM volker_race_data WHERE "team" = 'porsche kremer racing'

Question: Which Class has a Chassis of Mazda 787B?
SQL: SELECT "class" FROM volker_race_data WHERE "chassis" = 'mazda 787b'

Question: What Year has a Tyre of D, and Chassis of Mazda 787?
SQL: SELECT "year" FROM volker_race_data WHERE "tyre" = 'd' AND "chassis" = 'mazda 787'

Question: What is the total number of Laps that's got a Year less than 1987?
SQL: SELECT SUM("laps") FROM volker_race_data WHERE "year" < 1987