CREATE TABLE "gsm_900_gsm_1800_and_egsm_egsm_900" (
  "system" text,
  "band" real,
  "uplink_m_hz" text,
  "downlink_m_hz" text,
  "channel_number" text
);

Question: What band is the highest and has a System of gsm-450?
SQL: SELECT MAX("band") FROM "gsm_900_gsm_1800_and_egsm_egsm_900" WHERE "system"='gsm-450';