CODE EXAMPLE FOR CSHARP

c# lambda join two tables

    var UserInRole = db.UserProfiles.
        Join(db.UsersInRoles, u => u.UserId, uir => uir.UserId,
        (u, uir) => new { u, uir }).
        Join(db.Roles, r => r.uir.RoleId, ro => ro.RoleId, (r, ro) => new { r, ro })
        .Where(m => m.r.u.UserId == 1)
        .Select (m => new AddUserToRole
        {
            UserName = m.r.u.UserName,
            RoleName = m.ro.RoleName
        });