CREATE TABLE "fleet_history" (
  "aircraft" text,
  "introduced" real,
  "retired" text,
  "seating" text,
  "notes" text
);

Question: When was the aircraft introduced that could seat 115 people?
SQL: SELECT AVG("introduced") FROM "fleet_history" WHERE "seating"='115';

Question: What year was the aircraft retired when it was replaced by 737-300s?
SQL: SELECT "retired" FROM "fleet_history" WHERE "notes"='replaced by 737-300s';

Question: What aircraft was introduced in 2004 and has a retired of —?
SQL: SELECT "aircraft" FROM "fleet_history" WHERE "retired"='—' AND "introduced"=2004;

Question: Which aircraft has 148/9 seating?
SQL: SELECT "aircraft" FROM "fleet_history" WHERE "seating"='148/9';

Question: How many people can be seated on the aircraft that was introduced in 2008 and has notes of in service?
SQL: SELECT "seating" FROM "fleet_history" WHERE "notes"='in service' AND "introduced"=2008;