Computed columns and functions?

Hi all,

I’d like to set up a computed column that uses a function to derive its data, but can’t seem to find any information on how to do this.  My issue, specifically, is this:

I have a user table and an account activity table, which contains records of debits and credits to an account, user id as FK.  I’d like to create a computed column within my user table to show the user’s current balance (sum of credits minus sum of debits).  I’ve written a sql query to compute this when passed in a user id as an argument, but I can’t figure out how to create the computed column.

Any tips would be much appreciated.

Thanks,

David Benoff