Question: Name the successor for Not filled this congress
SQL: SELECT "Successor" FROM "1-225200-4" WHERE "Date successor seated" = 'Not filled this congress';

Question: Name the district for  Rep. Warren R. Davis died during previous congress
SQL: SELECT "District" FROM "1-225200-4" WHERE "Reason for change" = 'Rep. Warren R. Davis died during previous congress';

Question: Name the total number of reason for change for Not filled this congress
SQL: SELECT COUNT("Reason for change") FROM "1-225200-4" WHERE "Date successor seated" = 'Not filled this congress';

Question: Name the vacator for Resigned February 26, 1836 because of ill health
SQL: SELECT "Vacator" FROM "1-225200-4" WHERE "Reason for change" = 'Resigned February 26, 1836 because of ill health';