Perl hashes: is there some way of adding more data to the value associated with an existing key?

[mertserger]

I have some data I have extracted using SQl from a database. It takes the form of a list of two related values, which are an id number and then a value. Unfortunately the id number can be in the list more than once with a different value in the second column:

1 A
1 B
2 B
4 X
5 V

etc. I really need this to end up in a hash where the key is the id number but the value is the combined values of all the second columns, so in the made-up example above key "1" would relate to a value "A B". I know how to create a hash which would either take the first pair or last pair of key/value but I am struggling to see how you could update the value for the key so that it would contain all the values associated with that key.