How to retrieve data from multiple tables using Entity Framework

Question

I'm new to Entity Framework, and working on Boys & Girls Hostel Application. I decided to develop it as a WCF Service.

I have two tables

1. Master

Tbl_Room

• Rm_no int (PK)
• Rm_Name varchar
• RentPerBed money

• SharingLevel int

  1. Child

Tbl_Bed

• Sr_no (PK)
• Rm_no int (FK)
• Bed_no int
• Status int

I wrote the following function to retrieve data for the available beds but I'm getting an error ...and I'm confused about how I can do this...

public IEnumerable<Tbl_Room> Available()
{
    var avilableRoomWithBed = (from r in db.Tbl_Room
                               join s in db.Tbl_Bed on r.Rm_No equals s.Rm_No
                               where s.Status == 0
                               select new Tbl_Room()
                               {
                                   Rm_No = r.Rm_No,
                                   Rm_Name = r.Rm_Name,
                                   Floar = r.Floar,
                                   RentPerBed = r.RentPerBed
                               }).ToList();

     return avilableRoomWithBed.ToList();
}

Here I want to retrieve Bed_no which have a status of 0 ie available

I am confused about the return type of IEnumerable and what I have to return

Answer 1

You are approaching your EF like SQL - if you've got your relationships set up in the class correctly (ie a navigation property called Beds on Tbl_Room) then you can do the following.

var avilableRoomWithBed = from r in db.Tbl_Room
                          where r.Beds.Any(b => b.Status == 0)
                          select r;