user: Question: What is the IcAO of Frankfurt?
Columns: ['City', 'Country', 'IATA', 'ICAO', 'Airport']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Akureyri', 'Iceland', 'AEY', 'BIAR', 'Akureyri Airport']
SQL:

assistant: SELECT "ICAO" FROM "Table" WHERE "City" = 'Frankfurt';