tailieunhanh - Hướng dẫn học Microsoft SQL Server 2008 part 157

Kinh doanh thông minh ■ NotTop20ProductList: Xây dựng danh sách của tất cả mọi thứ không nằm trong top 20. Các nhà điều hành thiết lập''''trừ (-) được dùng để loại bỏ trong 20 sản phẩm hàng đầu trong danh sách của tất cả các sản phẩm. | PartX Business Intelligence NotTop20Prod uctList Builds the list of everything not in the top 20. The except set operator - is used to remove the top 20 products from the list of all products. That list is filtered to exclude empty members and is in turn ordered by order count descending. Average Top20ProductList Order Count Calculates the average order count across the set of top 20 products. Similar aggregate functions including SUM MIN MAX and MEDIAN share this syntax AVG set numeric_expression . In practice this calculation would likely be implemented as part of the next calculation but it s included here to show one calculation depending on another. Diffe rence from Top20 Products Difference between a given product s order count and the top 20 average. Top 20 Products Created as part of the product hierarchy to get a row to display showing the top 20 average. Because this row will display for a couple of measures the numeric_expression is omitted so that it is calculated in the context of the cell being displayed. Dimension considerations There are several things to understand about dimensions and the properties of the cube being queried as they affect query execution including the following MdxMissingMemberMode This dimension property when set to true causes invalid members specified as part of a query to be ignored without generating an error. For example if an axis is defined as Product . Product . Mountain-100 Silver 38 Product . Product . Banana and Banana is not a valid product name then no error will be generated. Instead the result will list the mountain bike and not the fruit. When MdxMissingMemberMode is set to false an error is generated for invalid member names. MDX scripts calculations described within the cube definition always throw an error for missing members regardless of this property setting. IgnoreUnrelatedDimensions When true this measure group property tells MDX to ignore dimensions unrelated to a measure being queried. For example the .