public bool ValidateNickName(string nickname, out ICollection <string> validationErrors) { validationErrors = new List <string>(); int count = 0; using (IDbConnection connection = new NpgsqlConnection(ConnectionString.ConnVal("dbConn"))) { var output = connection.QuerySingle <int>($@"SELECT COUNT(*) FROM player WHERE Nickname = @Nickname", new { Nickname = nickname }); count = output; } if (count > 0) { validationErrors.Add("Användarnamnet finns redan, välj ett annat"); } return(validationErrors.Count == 0); }