entity framework select last month records

Question

I have employee salary table that contains :

public partial class S_EmployeeSalary
    {
        public int SalaryId { get; set; }
        public int TypeId         


        

Answer 1

Depending if you want the last month or last 30 days (question is unclear)

This is for the previous month:

var startOfTthisMonth = new DateTime(DateTime.Today.Year, DateTime.Today.Month, 1);       
var firstDay = startOfTthisMonth.AddMonths(-1);
var lastDay = startOfTthisMonth.AddDays(-1);

IQueryable<S_EmployeeSalary> moduleItems = db.S_EmployeeSalary
    .Include(x => x.C_UserItems)
    .Where(x => x.TypeId == typeId && 
                x.SalaryDate >= firstDay &&
                x.SalaryDate <= lastDay);

This is for the previous 30 days:

var firstDay = DateTime.Today.AddDays(-30);

IQueryable<S_EmployeeSalary> moduleItems = db.S_EmployeeSalary
    .Include(x => x.C_UserItems)
    .Where(x => x.TypeId == typeId && 
                x.SalaryDate >= firstDay);

Answer 2

looks like this part is not going to return a result since it cant be bigger and smaller than 30 at the same time.

DbFunctions.DiffDays(x.SalaryDate, DateTime.Now) > 30 && DbFunctions.DiffDays(x.SalaryDate, DateTime.Now) < 30)