Question

I have a DataTable containing two columns, both of which is a list of ID’s, with a many-many relationship:

  ResourceID    AttributeID
  ----------    -----------
  1             1
  1             2
  1             3
  2             1
  2             3
  3             3

etc…

Given a list of AttributeID’s, I want to obtain a list of ResourceID’s that have ALL the supplied AttributeID’s.

I initially thought to do this:

    string[] attributes = "....";
    dv.RowFilter = "AttributeID in (" + String.Join(",", attributes) + ")";

    return dv.ToTable(true, "ResourceID").AsEnumerable().Select(x => (int)x[0]).ToList();

but that gives me a list that have ANY of the supplied AttributeID’s.

My list of attributes is currently a string array, but that can be changed if necessary. My result set is currently returned as a List of ResourceID’s, but that’s negotiable too.

Thanks in advance!

Answer 1

For anybody who is looking to do the same thing, here’s the solution that I found – essentially grouping my result set and counting the number of items in each group to check that it matches the number of items in my list of supplied attributes.

dv.RowFilter = "AttributeID in (" + String.Join(",", attributes) + ")";

List<int> Resources =  (from a in dv.ToTable().AsEnumerable()
         group a by (int)a["ResourceID"] into grp
         where grp.Count() == attributes.Length
         select grp.Key).ToList<int>();