user: Question: When did an event take place in the City of Copenhagen?
Columns: ['Date', 'City', 'Event', 'Winner', 'Prize']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['10–14 September 2008', 'Barcelona', 'EPT Barcelona Open', 'Sebastian Ruthenberg', '€1,361,000']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "City" = 'Copenhagen';