LINQ und Datatables

allgemeine (untypisierte) Datatable
var res = from x in dt.AsEnumerable() select x.Field(c.ColumnName);

join zweier typisierter Datasets:
var rsInner = from s in dtSource
join c in dtComp on s.FullName equals c.FullName
where s.Nullable!=c.Nullable || s.MaxLength!=c.MaxLength || s.Type!=c.Type
select new { s.TableName, s.ColumnName,
s.Nullable, cNullAble = c.Nullable,
s.MaxLength, cMaxL = c.MaxLength,
s.Type, cType = c.Type};