Tất cả các sản phẩm bằng cách lãnh thổ vào năm Danh mục sản phẩm theo vùng của bộ phận sản phẩm năm theo vùng năm Tất cả các sản phẩm của khu vực Danh mục sản phẩm năm của tất cả các cửa hàng của bộ phận sản phẩm năm bởi tất cả các cửa hàng của năm Tất cả các sản phẩm của tất cả các cửa hàng năm của các bảng thực tế tổng hợp có nguồn gốc từ một đơn bảng thực tế cơ sở. Bảng tổng hợp có nguồn gốc thực tế. | 300 DATA QUALITY A KEY TO SUCCESS System conversions. Trace the evolution of order processing in any company. The company must have started with a file-oriented order entry system in the early 1970s orders were entered into flat files or indexed files. There was not much stock verification or customer credit verification during the entry of the order. Reports and hard-copy printouts were used to continue with the process of executing the orders. Then this system must have been converted into an online order entry system with VSAM files and IBM s CICS as the online processing monitor. The next conversion must have been to a hierarchical database system. Perhaps that is where your order processing system still remains as a legacy application. Many companies have moved the system forward to a relational database application. In any case what has happened to the order data through all these conversions System conversions and migrations are prominent reasons for data pollution. Try to understand the conversions gone through by each of your source systems. Data aging. We have already dealt with data aging when we reviewed how over the course of many years the values in the product code fields could have decayed. The older values lose their meaning and significance. If many of your source systems are old legacy systems pay special attention to the possibility of aged data in those systems. Heterogeneous system integration. The more heterogeneous and disparate your source systems are the stronger is the possibility of corrupted data. In such a scenario data inconsistency is a common problem. Consider the sources for each of your dimension tables and the fact table. If the sources for one table are several heterogeneous systems be cautious about the quality of data coming into the data warehouse from these systems. Poor database design. Good database design based on sound principles reduces the introduction of errors. DBMSs provide for field editing. RDBMSs enable .
