Highest Value in each Group using LINQ

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In this post, I will show you how to fetch the maximum value in each Group using LINQ

Let us consider you have the following class called Employees

C#

class Employees
{
    public int EmpId { get; set; }
    public int DeptId { get; set; }
    public int Salary { get; set; }
}

You want to find out the highest salary of an Employee in each Department. Here’s the LINQ query:

C#

List<Employees> emp = new List<Employees>();
// populate emp – demo by devcurry
// emp.Add(new Employees() { EmpId = 1, DeptId = 1, Salary = 20000 });

var highest = from e in emp
            group e by e.DeptId into dptgrp
              let topsal = dptgrp.Max(x => x.salary)
            select new
            {
                Dept = dptgrp.Key,
                TopSal = dptgrp.First(y => y.Salary == topsal).EmpId,
                MaximumSalary = topsal
            };

Here's a quick description. We first get the maximum salary in a department using

let topsal = dptgrp.Max(x => x.salary)

we then use the ‘topsal’ variable to compare it against the salary of an Employee in that department and then select the Empid

TopSal = dptgrp.First(y => y.Salary == topsal).EmpId

That's it and you will get the Employee with the highest salary in each department. To print the results, just use a loop and print the values - foreach(var a in highest){ }.

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About The Author

Suprotim Agarwal, ASP.NET Architecture MVP works as an Architect Consultant and provides consultancy on how to design and develop Web applications.

Suprotim is also the founder and primary contributor to DevCurry, DotNetCurry and SQLServerCurry. He has also written an EBook 51 Recipes using jQuery with ASP.NET Controls.

Follow him on twitter @suprotimagarwal