Guy in a Cube’s Adam looks at why the LastDate DAX function is returning the wrong date within Power BI Desktop. Breaking down a twitter conversation.

Here’s a great video demonstrating the power and flexibility of DAX with 50 real world examples you can download and follow along with the samples files.

Example Index:

1. (01:27) Filter Context, First Look
2. (04:40) CALCULATE to change Filter Context with a Boolean Filter
3. (05:10) CALCULATE and CALCULATETABLE DAX Functions
4. (06:28) What is a Boolean Filter?
5. (08:00) First look at the Overwrite Operator in CALCULATE. Merge the Internal Filter Context and External Filter Context
6. (09:45) CALCULATETABLE to change Filter Context with a Boolean Filter
7. (11:25) CALCULATE to perform Context Transition
8. (13:17) All Measures have a Hidden CALCULATE Function
9. (14:20) Boolean Filter is always converted to a FILTER & ALL DAX Function construction
10. (17:22) DAX Studio to look at FILTER and ALL Equivalent for a Boolean Filter
11. (20:00) VALUES rather than ALL in first argument of FILTER
12. (22:05) VALUES Function to bring a Variable into a Formula and use it as a condition for a Boolean Filter
13. (24:22) AND Logical Test – 4 Examples
14. (26:18) Can NOT use two different columns in a Boolean Filters
15. (28:30) OR Logical Test Boolean Formulas
16. (30:33) Can NOT Directly Compare Two Columns as a Boolean Filter. Keystone Pricing Examples.
17. (33:20) DAX Studio to see how FILTER and ALL delivers a table where we directly compare two columns for a DAX Measure
18. (34:00) Can NOT use MIN or MAX or other aggregate functions as a condition for a Boolean Filter
19. (34:00) Frequency Distribution DAX Formula. Learn about the COUNTROWS Function
20. (43:07) ALL DAX Function & Grand Totals. Learn about the Remove Operator in ALL DAX Function when you use it in the Filter argument of CALCULATE
21. (47:42) Look at Data Model for Power BI File for looking more closely at the Overwrite Operator
22. (49:00) Overwrite Operation. Second look at the Overwrite Operator in CALCULATE. Merge the Internal Filter Context and External Filter Context into the
23. Final Filter Context
24. (50:50) Reminder about ALL before we learn about ALLSELECTED. What is the problem that ALLSELECTED can solve?
25. (52:35) ALLSELECTED to create Grand Totals that respect the filtering in the PivotTable
26. (53:33) Context Transition is how ALLSELECTED gets to the Grand Total Cell Filter Context
27. (53:45) Hidden Context Transition for Measures in an Excel PivotTable or Power BI Visual
28. (54:45) ALLSELECTED and Context Transition, the Full Story
29. (56:17) Visual Example of when ALLSELECTED will not get back to the Filter Context of the Grand Total Cell in the Excel PivotTable or Power BI Visual
30. (57:18) Use ALLSELECTED DAX Function in CALCULATE Measures
31. (59:05) ALLSELECTED Functions works on Cross Tab Reports too !
32. (59:44) Example of Measure in Power BI Visual that uses ALLSELECTED and will not get back to the Filter Context of the Grand Total Cell Power BI Visual
33. (01:01:20) Look at new Data Model for next example
34. (01:02:20)First example of the KEEPFILTERS DAX Function to force an AND Logical Test rather than an Overwrite Operation
35. (01:06:55) What is a Complex Filter? What is a Complex Filter Reduction Error?
36. (01:08:56) How KEEPFILTERS can help solve a Complex Filter Reduction Error for Year Column in AVERAGEX.
37. (01:14:47) Why KEEPFILTERS is used in the New Quick Measure in Power BI
38. (01:16:33) How KEEPFILTERS can help solve a Complex Filter Reduction Error for Year Column and Month Column in CROSSJOIN in AVERAGEX
39. (01:18:30) Data Model solution to solve Complex Filter Reduction Error
40. (01:20:05) Determine if a filter is a complex filter with CROSSJOIN
41. (01:21:17) Expanded Table Concept & Relationships.
42. (01:26:50) Table Filters & Expanded Table as filters in the Filter argument of CALCULATE
43. (01:27:15) Expanded Table Filter with ALL Function. 2 Examples
44. (01:29:15) Table Filter to send a filter backwards across a Many-To-One Relationship. Great Visual for understanding this filter
45. (01:33:10) ALLEXCEPT DAX Function with an Expanded Column
46. (01:37:00) Examples of Time Intelligence Functions
47. (01:37:20) Measure for Revenue from Last Year. SAMPERIODLASTYEAR
48. (01:38:40) Measure for Revenue for Last Month. DATEADD and ISFILTERED DAX Functions
49. (01:41:32) Compare Excel and DAX Formulas
50. (01:43:10) Measure for % Change using IF, BLANK, DIVIDE and HASONEVALUE DAX Functions
51. (01:46:15) DAX Formula Evaluation Context Summary

Curbal shows you how to unpivot tables with DAX. (whether or not you should do it in DAX may be a different question)

She then unpivots them using Power Query so you can see the difference, and how Power Query can be faster and more efficient for cleaning data.

In another one of their great videos, Patrick from Guy in a Cube shows you how to combine Power BI Report Tooltips using DAX.  Don’t worry, it’s just a little bit of DAX!

In this video, Patrick from Guy in a Cube uses a little DAX, and the SelectedValue function, to get you some dynamic labels in your Power BI reports.