How to SELECT WHERE NOT EXIST using LINQ?

Question

I have to list all \"shift\" data to be assigned to an \"employee\" but shift data must not be included if it is already existing in employ

Answer 1

        Dim result2 = From s In mySession.Query(Of CSucursal)()
                      Where (From c In mySession.Query(Of CCiudad)()
                             From cs In mySession.Query(Of CCiudadSucursal)()
                             Where cs.id_ciudad Is c
                             Where cs.id_sucursal Is s
                             Where c.id = IdCiudad
                             Where s.accion <> "E" AndAlso s.accion <> Nothing
                             Where cs.accion <> "E" AndAlso cs.accion <> Nothing
                             Select c.descripcion).Single() Is Nothing
                      Where s.accion <> "E" AndAlso s.accion <> Nothing
                      Select s.id, s.Descripcion

Answer 2

How about..

var result = (from s in context.Shift join es in employeeshift on s.shiftid equals es.shiftid where es.empid == 57 select s)

Edit: This will give you shifts where there is an associated employeeshift (because of the join). For the "not exists" I'd do what @ArsenMkrt or @hyp suggest

Answer 3

The outcome sql will be different but the result should be the same:

var shifts = Shifts.Where(s => !EmployeeShifts.Where(es => es.ShiftID == s.ShiftID).Any());

Answer 4

First of all, I suggest to modify a bit your sql query:

 select * from shift 
 where shift.shiftid not in (select employeeshift.shiftid from employeeshift 
                             where employeeshift.empid = 57);

This query provides same functionality. If you want to get the same result with LINQ, you can try this code:

//Variable dc has DataContext type here
//Here we get list of ShiftIDs from employeeshift table
List<int> empShiftIds = dc.employeeshift.Where(p => p.EmpID = 57).Select(s => s.ShiftID).ToList();

//Here we get the list of our shifts
List<shift> shifts = dc.shift.Where(p => !empShiftIds.Contains(p.ShiftId)).ToList();

Answer 5

from s in context.shift
where !context.employeeshift.Any(es=>(es.shiftid==s.shiftid)&&(es.empid==57))
select s;

Hope this helps