user: Question: What is the date of successors formal installation when the reason for change is Resigned December 4, 1819?
Columns: ['State (class)', 'Vacator', 'Reason for change', 'Successor', 'Date of successors formal installation']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Alabama (2)', 'New seats', 'Alabama was admitted to the Union.', 'John W. Walker (DR)', 'Elected December 14, 1819']
SQL:

assistant: SELECT "Date of successors formal installation" FROM "Table" WHERE "Reason for change" = 'Resigned December 4, 1819';