Merging Data with LINQ

- 
var terms = from t in HRSystemDB.Terminations 
            select new { Month = t.TerminationDate.Month, 
                         Year = term1.TerminationDate.Year,
                         IsHire = false };
var hires = from emp in HRSystemDB.Persons.OfType<Employee>() 
            select new { Month = emp.HireDate.Month, 
                         Year = emp.HireDate.Year 
                         IsHire = true };

// Now we can merge the two inputs into one
var summary = terms.Concat(hires);

// And group the data using month or year
var res = from s in summary 
          group s by new { s.Year, s.Month } into g
          select new { Period = g.Key, 
                       Hires = g.Count(info => info.IsHire),  
                       Terminations = g.Count(info => !info.IsHire) }

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