CREATE TABLE "past_fleet" (
  "class" text,
  "type" text,
  "built" text,
  "number" real,
  "withdrawn" real
);

Question: Which class had a number under 4 and was built in 1988?
SQL: SELECT "class" FROM "past_fleet" WHERE "number"<4 AND "built"='1988';

Question: How many items withdrawn had numbers over 5?
SQL: SELECT COUNT("withdrawn") FROM "past_fleet" WHERE "number">5;

Question: What is the sum of numbers that had a type of Driving Van Trailer?
SQL: SELECT SUM("number") FROM "past_fleet" WHERE "type"='driving van trailer';