CREATE TABLE table_47309 ("Rank" TEXT, "Nation" TEXT, "Gold" FLOAT, "Silver" FLOAT, "Bronze" FLOAT, "Total" FLOAT)

What is the highest number of gold medals when the silver is less than 0?
SELECT MAX("Gold") FROM table_47309 WHERE "Silver" < '0'
SELECT MAX("Gold") FROM "table_47309" WHERE "Silver" < '0'