CREATE TABLE table_18454 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

What is the most first elected for james c. davis?
SELECT MAX("First elected") FROM table_18454 WHERE "Incumbent" = 'James C. Davis'
SELECT MAX("First elected") FROM "table_18454" WHERE "Incumbent" = 'James C. Davis'