CREATE TABLE table_797 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

When was incumbent John N. Tillman first elected?
SELECT MIN("First elected") FROM table_797 WHERE "Incumbent" = 'John N. Tillman'
SELECT MIN("First elected") FROM "table_797" WHERE "Incumbent" = 'John N. Tillman'