CREATE TABLE table_31938 ("Rank" TEXT, "Nation" TEXT, "Gold" FLOAT, "Silver" FLOAT, "Bronze" FLOAT, "Total" FLOAT)

Name the fewest gold for tanzania with bronze less than 0
SELECT MIN("Gold") FROM table_31938 WHERE "Nation" = 'tanzania' AND "Bronze" < '0'
SELECT MIN("Gold") FROM "table_31938" WHERE "Bronze" < '0' AND "Nation" = 'tanzania'