This problem can of course be solved using a loop, but loops are so repulsive
Assume a table with the following columns:
RowID - this is a unique value
MyValue - this is some kind of non-predictable data
GroupID - this is the value we want to set.
What I want to do is to assign the same group ID to all the rows that has the same MyValue. Remember that MyValue is not predictable.
/HL