CREATE TABLE table_63852 ("Airline" TEXT, "IATA" TEXT, "ICAO" TEXT, "Callsign" TEXT, "Commenced operations" FLOAT)

Which IATA has a ICAO of slk?
SELECT "IATA" FROM table_63852 WHERE "ICAO" = 'slk'
SELECT "IATA" FROM "table_63852" WHERE "ICAO" = 'slk'