CREATE TABLE "history" (
  "number" text,
  "serial_number" real,
  "into_service" text,
  "withdrawn" text,
  "scrapped" text
);

Question: Name the into service for dh1
SQL: SELECT "into_service" FROM "history" WHERE "number"='DH1';

Question: Name the withdrawn for example and serial number 579
SQL: SELECT "withdrawn" FROM "history" WHERE "into_service"='Example' AND "serial_number"=579;

Question: Name the into service for dh2
SQL: SELECT "into_service" FROM "history" WHERE "number"='DH2';

Question: Name the most serial number for feb 1994
SQL: SELECT MAX("serial_number") FROM "history" WHERE "scrapped"='Feb 1994';

Question: Name the number for 2004 scapped
SQL: SELECT "number" FROM "history" WHERE "scrapped"='2004';

Question: Name the into service for dh1
SQL: SELECT "into_service" FROM "history" WHERE "number"='DH1';