Samples of using selects with entity framework

Ef_Selects.cs

        public async Task<ICollection<Tuple<Site,ICollection<String>>>> GetSitesByUserIdAsync(int userId)
        {
            StringBuilder sb = new StringBuilder();
            Action<string> action = s => sb.Append(s);
            _context.Database.Log += action;

            var res= await _context.UserSiteAccesses
                .Where(p => p.UserId == userId && p.Accsess == "read")
                .Select(p => new RwTuple<Site,ICollection<String>>
                    {
                        Item1 = p.Site,
                        Item2 = _context.UserSiteAccesses
                            .Where(a 
                                => a.UserId == userId 
                                && a.SiteId==p.SiteId
                                )
                            .Select(a=>a.Accsess).ToList()
                    }
                )
                .ToListAsync();

            _context.Database.Log -= action;
            var sql = sb.ToString();
            return res.Select(x => x.ToTuple()).ToList();

        }
        
        public async Task<int> GetOwnerId(int siteId)
        {
            var selectionResult = await base._context.Sites
                .Where ( p => p.Id == siteId )
                .Select (s=>s.OwnerId)
                .FirstOrDefaultAsync();
            return selectionResult;
        }

        public async Task<List<Site>> GetSitesByUserId(int userId)
        {
            var sites = await base._context.UserSiteAccesses
                .Where(p => p.UserId == userId)
                .GroupBy(p=>p.Site)
                .Select(p => p.Key)
                .ToListAsync();

            return sites;
        }