I have three rows with three columns in one table
id type value 1 gold 1000.00 2 silver 32.21 3 platinum 1500.00
You could use a CASE clause like this:
CASE
$query = "UPDATE metals SET value = CASE id WHEN 1 THEN $gold WHEN 2 THEN $silver WHEN 3 THEN $plat END";
This seems a bit of overkill for just three rows, though.