vb.net barcode reader sdk 4: DAX: Overview in Microsoft Office

Generator UPC Code in Microsoft Office 4: DAX: Overview

intelligence (for example, year-to-date sales or year-on-year sales growth), and much, much more Many of these functions will be discussed in the course of this chapter

Nearly all of the examples in this chapter use Northwind data If you want to experiment (and you don t have the data yet), as well as read, you can refer to 1 to see how to import SQL Server Northwind 2 shows how to import Access Northwind or, alternatively, how to import Excel Northwind (available for download from this book s Web site), or even how to connect to a Northwind data feed

DAX formulas can be used to create calculated columns or calculated measures A calculated column is defined in the PowerPivot window when you add a new column to a PowerPivot table It doesn t matter which PowerPivot ribbon is current A measure is defined in an Excel worksheet containing a pivot table and/or pivot chart based on PowerPivot tables In order to create a measure, the focus must be in the pivot report or in the PowerPivot Field List for the PowerPivot Field List to display, you must first have the focus on the pivot report Then you can use the New Measure button in the Measures group of the PowerPivot ribbon in Excel If another ribbon is current, you can always right-click a table in the field list and choose Add New Measure

To create a calculated column, you must be in the PowerPivot window As shown earlier in the book, one way of creating (or adding) a calculated column is to click the Add button in the Columns group of the Design ribbon Or you can simply scroll until you see the first empty column, with the column header Add Column, and click in the column You then enter your DAX formula in the formula bar and press enter the formula bar lies between the ribbon and the table If you create or modify a calculated column, and you already have a pivot table, the PowerPivot Field List will alert you to the fact and present a Refresh button so the pivot table and field list can be updated with the change

Every row in the table will contain the result of the DAX formula in the calculated column, even if the result is an error or a blank value The context of the calculated column result is at the row level in the table Calculated columns have row context The result of the column for each row is usually fixed, although a refresh of the source data may result in a change if the source data has changed Some people refer to calculated columns as static data

As soon as you ve finished the formula and pressed enter, the column result is evaluated for each row This is true if you are in the default automatic calculation mode If you switch to manual calculation mode, the result is not evaluated until you press f or choose Calculate Now (as a reminder, this option is available in the Calculation Options drop-down Design ribbon, Calculations group) Whether the evaluation is performed automatically or manually, once the evaluation is complete, the results are materialized In other words, the calculated column is now a static part of your PowerPivot table and looks and behaves just like a normal, imported column Calculated columns are often used to extend or manipulate the data you ve already imported Just like regular columns, calculated columns are used as rows, columns, filters, or slicers in a pivot table Popular examples of calculated columns include parsing an existing column, concatenating existing columns, or denormalizing data by referencing a column in another PowerPivot table