CREATE TABLE table_12310 ("Res." TEXT, "Record" TEXT, "Opponent" TEXT, "Method" TEXT, "Event" TEXT, "Round" FLOAT, "Time" TEXT, "Location" TEXT)

Which Opponent has a Time of 0:38?
SELECT "Opponent" FROM table_12310 WHERE "Time" = '0:38'
SELECT "Opponent" FROM "table_12310" WHERE "Time" = '0:38'