CREATE TABLE table_18706 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

what's the district with candidates being william madison whittington (d) unopposed
SELECT "District" FROM table_18706 WHERE "Candidates" = 'William Madison Whittington (D) Unopposed'
SELECT "District" FROM "table_18706" WHERE "Candidates" = 'William Madison Whittington (D) Unopposed'