PowerPivot and DAX papers,posts,FAQs,webcasts,samples

Using DAX as a query language you will lack a fundamental feature like projection. In fact, DAX allows you add columns to an existing table, but you cannot simply remove some column from a table. In order to do that, you have to use SUMMARIZE, or you can use ADDCOLUMNS starting from a column that you want to include in the query output and that has to be unique for each row of the result.