user: Question: Which district has Joseph T. Johnson as an incumbent?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['South Carolina 1', 'George Swinton Legaré', 'Democratic', '1902', 'Re-elected']
SQL:

assistant: SELECT "District" FROM "Table" WHERE "Incumbent" = 'Joseph T. Johnson';