I'm looking at building a facility which allows querying for data with hierarchical filtering. I have a few ideas how I'm going to go about it but was wondering if there are any recommendations or suggestions that might be more efficient.

As an example imagine that a user is searching for a job. The job areas would be as follows.

1: Scotland
2: --- West Central
3: ------ Glasgow
4: ------ Etc
5: --- North East
6: ------ Ayrshire
7: ------ Etc

A user can search specific (ie Glasgow) or in a larger area (ie Scotland).

The two approaches I am considering are
1: keep a note of children in the database for each record (ie cat 1 would have 2, 3, 4 in its children field) and query against that record with a SELECT * FROM Jobs WHERE Category IN Areas.childrenField.
2: Use a recursive function to find all results who have a relation to the selected area

The problems I see from both are
1: holding this data in the db will mean having to keep track of all changes to structure
2: Recursion is slow and inefficent

Any ideas, suggestion or recommendations on the best approach? I'm using C# ASP.NET with MSSQL 2005 DB.