Освобождение ресурсов

            public static bool IsSchemaExistsInDB(UserConnection userConnection, EntitySchema entitySchema) {
                    string sqlText = userConnection.DBEngine.GetIsEntitySchemaExistSqlText();
                    var checkSchemaExistCustomQuery = new CustomQuery(userConnection, sqlText)
                           .WithParameter("EntitySchemaName", entitySchema.Name);
                    if (sqlText.Contains("@DBSchemaName") || sqlText.Contains(":DBSchemaName")) {
                           checkSchemaExistCustomQuery.WithParameter("DBSchemaName", userConnection.DBEngine.CurrentSchemaName);
                    }
                    using (DBExecutor dbExecutor = userConnection.EnsureDBConnection()) {
                           using (IDataReader dataReader = checkSchemaExistCustomQuery.ExecuteReader(dbExecutor)) {   // (!)
                                  return dataReader.Read();
                           }
                    }
             }