Write a linq query to find the N-th highest salary of employee. Also the query shoudl be able to handle the Tie situation i.e. the program has to return a collection when multiple employees have equal salary.

 Posted by Niladri.Biswas on 7/30/2012 | Category: C# Interview questions | Views: 7021 | Points: 40
Answer:

Let us first make the environment.First let us declare an Employee class

class Employee

{
public string EmpName { get; set; }
public int Salary { get; set; }
}


Then populate some records to it

private static List<Employee> GetEmpRecord()

{
List<Employee> empCollection = new List<Employee>();
empCollection.Add(new Employee { EmpName = "Emp1", Salary = 10000 });
empCollection.Add(new Employee { EmpName = "Emp2", Salary = 3456 });
empCollection.Add(new Employee { EmpName = "Emp3", Salary = 14256 });
empCollection.Add(new Employee { EmpName = "Emp4", Salary = 15000 });
empCollection.Add(new Employee { EmpName = "Emp5", Salary = 10000 });
empCollection.Add(new Employee { EmpName = "Emp6", Salary = 6000 });
empCollection.Add(new Employee { EmpName = "Emp7", Salary = 2000 });
empCollection.Add(new Employee { EmpName = "Emp8", Salary = 5000 });
empCollection.Add(new Employee { EmpName = "Emp9", Salary = 7000 });
empCollection.Add(new Employee { EmpName = "Emp10", Salary = 7000 });
return empCollection;
}

Finally let us write the program

var empCollection = GetEmpRecord();

int whichEmpSalary = 3;

var employees = (from emp in empCollection
group emp by emp.Salary into g
orderby g.Key descending
select new
{
EmpRecord = g.ToList()
}).ToList();

employees[whichEmpSalary - 1].EmpRecord
.ForEach(i => Console.WriteLine("Emp Name {0} earns {1}", i.EmpName, i.Salary));

Console.ReadKey();


Let us analyze the program. First we are grouping up the Employee Record Set by their salary.If we put a break point there and check , we will find that there are a total of 8 elements since both Emp1 and Emp5 are earning 10000 while Emp9 and Emp10 are earning 7000 each.But it is not sorted. In order to sort the record set, we have introduce the order by clause that will guaranteed to bring the result in a sorted order.Finally we are projecting the record using the select statement.At this stage we will get the count as 8 only but with sorted record set.Suppose we want to find out the third highest salary which should be "Emp1" and "Emp5" (both earning 10000 each). The first will be "Emp4" with 15000 and second is "Emp3" with Salary = 14256.Since it is a collection, we can use index as shown under to obtain the desired result.
var result = employees[2];

will give the desire result.
Output
Emp Name Emp1 earns 10000

Emp Name Emp5 earns 10000


//Lambda version
empCollection

.GroupBy(g=>g.Salary)
.OrderByDescending(o=>o.Key)
.Select(s=>new{EmpRecord = s.ToList()})
.ToList()[whichEmpSalary - 1].EmpRecord
.ForEach(i => Console.WriteLine("Emp Name {0} earns {1}", i.EmpName, i.Salary));


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