CREATE TABLE table_204_49 (id NUMBER, "city" CLOB, "country" CLOB, "iata" CLOB, "icao" CLOB, "airport" CLOB, "commenced" NUMBER, "ended" CLOB)

how long did tigerair fly into chiang mai ?
SELECT "ended" - "commenced" FROM table_204_49 WHERE "city" = 'chiang mai'
SELECT "ended" - "commenced" FROM "table_204_49" WHERE "city" = 'chiang mai'