Basically you would use the formatter in my previous post to create an array of the $_GET.noc options using Set Value named nocsplitvalue:
if $_GET.noc was 1763
$_GET.noc.nocsplit() you would give you an array of [1,17,176,1763]
In your database query, you can use this array with an IN operator for each of noc1, noc2, noc3
i.e. WHERE noc1 IN nocsplitvalue OR noc2 IN nocsplitvalue OR noc3 IN nocsplitvalue