IQ

Find 2nd highest salary using sql
Select TOP 1 Salary
from (SELECT DISTINCT TOP 2 Salary from Employee ORDER BY Salary ASC)
a ORDER BY Salary DESC

Find 2nd highest salary using LINQ

var employee = Employees
                         .OrderByDescending(e => e.Salary)
                         .Skip(1)  //skip(N-1) N is 2
                         .First();

If multiple employees may have equal salary and you wish to return an IEnumerable of all the employees with the second-highest salary you could do

var employees = Employees
                           .GroupBy(e => e.Salary)
                          .OrderByDescending(g => g.Key)
                          .Skip(1)
                           .First();
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Call Server Side Code using ASP.NET AJAX and jQuery AJAX
using System.Web.Services;
     try
     {
        //Do here server event
     }
     catch (Exception)
     {
       throw;
     }
}
function MyFunction(Param1, Param2) {                                              
    $.ajax({
        type: "POST",
        url: "MyPage.aspx/MyMethod",
        data: "{ Param1: '" + Param1+ "',Param2: '" + Param2 + "'}",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        cache: "false",
        success: function (msg) {
            // On success                
        },
        Error: function (x, e) {
            // On Error
        }
    });