user: Question: Which area served has a Callsign of 5DDN?
Columns: ['Callsign', 'Area served', 'Frequency', 'Band', 'Fate', 'Freq currently', 'Purpose']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['5AD', 'Adelaide', '1323', 'AM', 'Swapped calls with 5DDN to become 5DN in 1994', '5DN', 'Commercial']
SQL:

assistant: SELECT "Area served" FROM "Table" WHERE "Callsign" = '5DDN';