CREATE TABLE table_18311 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

What district did Dave Treen serve?
SELECT "District" FROM table_18311 WHERE "Incumbent" = 'Dave Treen'
SELECT "District" FROM "table_18311" WHERE "Incumbent" = 'Dave Treen'