Frequency MHz of 93.7 has what class?
CREATE TABLE "oklahoma" (
  "call_sign" text,
  "frequency_m_hz" real,
  "city_of_license" text,
  "erp_w" real,
  "class" text,
  "fcc_info" text
);
SELECT "class" FROM "oklahoma" WHERE "frequency_m_hz"=93.7;