how to use distinct in c# code example

Example 1: C# .NET Core linq Distinct

var distinctUsers = allUsers
    .GroupBy(x => x.UserId)
    .Select(x => x.First())
    .ToList();

Example 2: c# distinct dictionary

var temp = _context.PlayerStats.Where(T => T.allianceId == _surf).Select(T => T.guildId).Distinct();
                var result = new Dictionary<string, string>();
                foreach (var item in temp)               
                    result[item] = _context.PlayerStats.FirstOrDefault(T => T.guildId == item).guildName;               
                return View(result);