Euclidean distance between two sets of tuples

Hi all,
I would like to ask if there exists a function to calculate the
Euclidean distance between two rows of the same table.
Obviously, the distance between two non-numeric fields should be 0 if
they are the same value, 1 otherwise.

In general, I need to compute an average distance between the subsets of
rows, computed pairwise.
Example:
- Set 1: 10 rows
- Set 2: 15 rows
- Distances computed 150
I just need the value 1/150*(Sum of all the computed Euclidean distances).

I could write a procedure, but it would be nice if there already exists
a function which at least computes a single Euclidean function between
two rows.

Any suggestion?

Thank you.