CREATE TABLE table_715 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

What is the minimum first elected for ed markey?
SELECT MIN("First elected") FROM table_715 WHERE "Incumbent" = 'Ed Markey'
SELECT MIN("First elected") FROM "table_715" WHERE "Incumbent" = 'Ed Markey'