Table: rail_classes
Columns: class
operator
number
year_built
cars_per_set
unit_numbers

Question: What is the smallest number for Cars per Set built in 1977-1979 larger than 32?
SQL: SELECT MIN("cars_per_set") FROM rail_classes WHERE "year_built" = '1977-1979' AND "number" > 32

Question: What unit has cars per set larger than 9 built in 1982?
SQL: SELECT "unit_numbers" FROM rail_classes WHERE "cars_per_set" > 9 AND "year_built" = '1982'

Question: What is the largest number of cars per set that is less than 9?
SQL: SELECT MAX("number") FROM rail_classes WHERE "cars_per_set" < 9

Question: What year was the class 253 larger than 18 built?
SQL: SELECT "year_built" FROM rail_classes WHERE "class" = 'class 253' AND "number" > 18