Automatically Generating Date Dimension Tables In Excel 2016 Power Pivot

As you probably know, whenever you are doing any kind of date or time-based calculations in DAX you should always have a separate Date table in your Power Pivot model. There are a number of ways of building these tables (see, for example, my Power Query query here) but they are all a bit of a hassle – which is why it’s so cool that, in Excel 2016, you can get one built automatically inside the Power Pivot window.

Consider the following table of sales data on an Excel worksheet:


With this table loaded into the Data Model (and the Order Date column recognised as containing data of the Date data type), when you go to the Design tab in the Power Pivot window you’ll see the new Date Table button enabled:


Clicking on the New button will add a new date table to the Data Model, called Calendar:


This table is automatically marked as the Date Table in your model.

The table contains a continuous range of dates starting from the beginning of the year of the earliest date found in any column in any table in your Data Model, up to the end of the year containing the latest date found in any column in any table in your Data Model. Obviously, this means that your table could contain a very large date range if, for example, you have a Customer table containing a Date Of Birth column. Luckily, you also have the option of manually configuring the range of dates used by clicking the Update Range button:


One other thing to point out is that the resulting table is a table like any other, so you can add, delete or rename columns as you wish. You should also be able to set the table back to its default state by using the Set Default menu option, but I couldn’t make that work (possibly it hasn’t been implemented yet – this post was written using the Excel 2016 Preview).

If you do make changes like adding calculated columns, such as the Month Year calculated column shown below:


You can then click the Save Configuration button to save the current state of the table as your default. This means that the next time you create a new Date table in the same workbook, the table will include any customisations. However these changes don’t seem to be applied in Date tables created in new workbooks – maybe this will also change before RTM?

All in all, this is a very handy feature that will save Power Pivot modellers a lot of time. I wonder if it uses the new Calendar() or CalendarAuto() DAX functions under the covers?

Using DateDiff() To Calculate Time Intervals In DAX

One of the most useful new additions to DAX in Excel 2016 and the Power BI Designer is the DateDiff() function. It does exactly what you would expect: calculate the amount of time in between two dates, and express that value as either seconds, minutes, hours, days, weeks, months, quarters or years.

Here’s a very simple table of dates:


With this table loaded into the Power BI Designer, you can add new calculated columns to the table by clicking the New Column button on the ribbon. Here are two calculated column definitions that give the number of days and the number of years between the Start Date and the End Date on each row:

DayDurationColumn = 
DATEDIFF(MyTable[Start Date], MyTable[End Date], DAY)

YearDurationColumn = 
DATEDIFF(MyTable[Start Date], MyTable[End Date], YEAR) 

The output is pretty much what you’d expect:


It is of course also possible to create measures that use the DateDiff() function to, for example:

YearDurationMeasure = 
FIRSTDATE(MyTable[Start Date]), 
LASTDATE(MyTable[End Date]), 


All very straightforward, then, and much easier than having to calculate these values yourself.

Using SelectColumns() To Alias Columns In DAX

A few years ago I wrote this post on how to alias columns in a table in DAX, using a combination of AddColumns() and Summarize(). The good news is that in Excel 2016/the Power BI Designer/SSAS Tabular 2016 there’s a new DAX function specifically for this purpose: SelectColumns(). Here’s an example of how it can be used:

Imagine you have the following source table, called Products:


You can write a DAX query to get all the rows and columns from this table like so:


Here’s the output of that query in DAX Studio (and remember, DAX Studio can connect to data loaded into the Power BI Designer, which is what I’m doing here):


You can alias the columns in this table using SelectColumns() very easily, like so:

    "Column One", Products[Product],
    "Column Two", Products[Colour]

Here’s the output:


The syntax for SelectColumns() is straightforward: the first parameter is a table expression, and after that there are pairs of parameters consisting of:

  • A new column name
  • An expression returning a column from the table given in the first parameter

As you can see in the output of the query above, I’ve renamed the Product column “Column One” and the Colour column “Column Two”.

This means I can now crossjoin a table with itself without needing to worry about conflicting column names, like so:

        "Column One", Products[Product],
        "Column Two", Products[Colour]


One other interesting thing to note about SelectColumns() is that it allows you to do projection in a DAX query easily – as Marco notes here, it was possible before but it wasn’t pleasant. For example, the query:

    "Just Colour", Products[Colour]



Notice how there are three rows in the output here and that the value Green occurs twice. If you’re a true DAX afficionado, you might get excited about that.

Documentation For New Excel 2016 DAX Functions

Microsoft has published documentation for the new DAX functions in the Excel 2016 preview here:

There’s a lot of detail, including examples (although the ConcatenateX() page isn’t live at the time of writing – but I’ve blogged about that already), so it’s well worth reading through.

NaturalInnerJoin And NaturalLeftOuterJoin DAX Functions In Excel 2016

Continuing my series on new DAX functions in Excel 2016, here are two more: NaturalInnerJoin() and NaturalLeftOuterJoin(). Both do pretty much what you’d expect.

Consider the following two tables in an Excel worksheet, called ColourFruit and FruitPrice:


With these tables loaded into the Excel Data Model as linked tables, the next step is to create a relationship between the tables on the Fruit column:


Both functions only work with two tables that have an active relationship between them, and both take two tables from the Excel Data Model as parameters. Once you’ve done that you can use these functions in a DAX query.

The queries

evaluate naturalinnerjoin(ColourFruit,FruitPrice)


evaluate naturalinnerjoin(FruitPrice,ColourFruit)

…both perform an inner join between the two tables on the Fruit column and both return the same table:


The query

evaluate naturalleftouterjoin(ColourFruit,FruitPrice)



The query

evaluate naturalleftouterjoin(FruitPrice,ColourFruit)



For NaturalLeftOuterJoin() the table given in the first parameter is on the left-hand side of the left outer join, so all rows from it are returned, whereas the table in the second parameter is on the right-hand side of the join so only the matching rows are returned.

What’s New In The Excel 2016 Preview For BI?

Following on from my recent post on Power BI and Excel 2016 news, here are some more details about the new BI-related features in the Excel 2016 Preview. Remember that more BI-related features may appear before the release of Excel 2016, and that with Office 365 click-to-run significant new features can appear in between releases, so this is not a definitive list of what Excel 2016 will be able to do at RTM but a snapshot of functionality available as of March 2015 as outlined in this document and which I’ve found from my own investigations. When I find out more, or when new functionality appears, I’ll either update this post or write a new one.

Power Query

Yesterday, in the original version of my post, I mistakenly said that Power Query was a native add-in in Excel 2016: that’s not true, it’s not an add-in at all, it’s native Excel functionality. Indeed you can see that there is no separate Power Query tab any more, and instead there is a Power Query section on the Data tab instead:


Obviously I’m a massive fan of Power Query so I’m biased, but I think this is a great move because it makes all the great Power Query functionality a lot easier to discover. There’s nothing to enable – it’s there by default – although I am a bit worried that users will be confused by having the older Data tab features next to their Power Query equivalents.

There are no new features for Power Query here compared to the latest version for Excel 2013, but that’s what I expected.

Excel Forecasting Functions

I don’t pretend to know anything about forecasting, but I had a brief play with the new Forecast.ETS function and got some reasonable results out of it as seen in the screenshot below:


Slicer Multiselect

There’s a new hammer icon on a slicer, which, when you click it, changes the way selection works. The default behaviour is the same as Excel 2013: every time you click on an item, that item is selected and any previous selection is lost (unless you were holding control or shift to multiselect). However with the hammer icon selected each new click adds the item to the previously selected items. This is meant to make slicers easier to use with a touch-screen.


Time Grouping in PivotTables

Quite a neat feature this, I think. If you have a table in the Excel Data Model that has a column of type date in it, you can add extra calculated columns to that table from within a PivotTable to group by things like Year and Month. For example, here’s a PivotTable I built on a table that contains just dates:


Right-clicking on the field containing the dates and clicking Group brings up the following dialog:


Choosing Years, Quarters and Months creates three extra fields in the PivotTable:


And these fields are implemented as calculated columns in the original table in the Excel Data Model, with DAX definitions as seen here:


Power View on SSAS Multidimensional

At-bloody-last. I haven’t installed SSAS on the VM I’m using for testing Excel 2016, but I assume it just works. Nothing new in Power View yet, by the way.

Power Map data cards

Not sure why this is listed as new in Excel 2016 when it seems to be the same feature that appeared in Excel 2013 Power Map recently:

Power Pivot

There isn’t any obvious new functionality in the Power Pivot window, but it’s clear that the UI in general and the DAX formula editor experience in particular has been improved.


Suggested Relationships

When you use fields from two Excel Data Model tables that have no relationship between them in a PivotTable, you get a prompt to either create new relationships yourself or let Excel detect the relationships:


Renaming Tables and Fields in the Power Pivot window

In Excel 2013 when you renamed tables or fields in the Excel Data Model, any PivotTables that used those objects had them deleted. Now, in Excel 2016, the PivotTable retains the reference to table or field and just displays the new name. What’s even better is that when you create a measure or a calculated column that refers to a table or column, the DAX definition of the measure or calculated column gets updated after a rename too.


There are lots of new DAX functions in this build. With the help of the mdschema_functions schema rowset and Power Query I was able to compare the list of DAX functions available in 2016 with those in 2013 and create the following list of new DAX functions and descriptions:

DATEDIFF			Returns the number of units (unit specified in Interval) 
			between the input two dates
CONCATENATEX		Evaluates expression for each row on the table, then 
			return the concatenation of those values in a single string 
			result, separated by the specified delimiter
KEYWORDMATCH		Returns TRUE if there is a match between the 
			MatchExpression and Text. 
ADDMISSINGITEMS		Add the rows with empty measure values back.
CALENDAR			Returns a table with one column of all dates between 
			StartDate and EndDate 
CALENDARAUTO		Returns a table with one column of dates 
			calculated from the model automatically
CROSSFILTER		Specifies cross filtering direction to be used in 
			the evaluation of a DAX expression. The relationship is 
			defined by naming, as arguments, the two columns that 
			serve as endpoints
CURRENTGROUP		Access to the (sub)table representing current 
			group in GroupBy function. Can be used only inside GroupBy 
GROUPBY			Creates a summary the input table grouped by the 
			specified columns
IGNORE			Tags a measure expression specified in the call to 
			SUMMARIZECOLUMNS function to be ignored when 
			determining the non-blank rows.
ISONORAFTER		The IsOnOrAfter function is a boolean function that 
			emulates the behavior of Start At clause and returns 
			true for a row that meets all the conditions mentioned as 
			parameters in this function.
NATURALINNERJOIN		Joins the Left table with right table using the 
			Inner Join semantics
NATURALLEFTOUTERJOIN	Joins the Left table with right table 
			using the Left Outer Join semantics
ROLLUPADDISSUBTOTAL		Identifies a subset of columns specified 
			in the call to SUMMARIZECOLUMNS function that should be 
			used to calculate groups of subtotals
ROLLUPISSUBTOTAL		Pairs up the rollup groups with the column 
SELECTCOLUMNS		Returns a table with selected columns from the table 
			and new columns specified by the DAX expressions
SUBSTITUTEWITHINDEX		Returns a table which represents the semijoin of two 
			tables supplied and for which the common set of 
			columns are replaced by a 0-based index column. 
			The index is based on the rows of the second table 
			sorted by specified order expressions.
SUMMARIZECOLUMNS		Create a summary table for the requested 
			totals over set of groups.
GEOMEAN			Returns geometric mean of given column 
GEOMEANX			Returns geometric mean of an expression 
			values in a table.
MEDIANX			Returns the 50th percentile of an expression 
			values in a table.
PERCENTILE.EXC		Returns the k-th (exclusive) percentile of 
			values in a column.
PERCENTILE.INC		Returns the k-th (inclusive) percentile of 
			values in a column.
PERCENTILEX.EXC		Returns the k-th (exclusive) percentile of an 
			expression values in a table.
PERCENTILEX.INC		Returns the k-th (inclusive) percentile of an 
			expression values in a table.
PRODUCT			Returns the product of given column reference.
PRODUCTX			Returns the product of an expression 
			values in a table.
XIRR			Returns the internal rate of return for a schedule of 
			cash flows that is not necessarily periodic
XNPV			Returns the net present value for a schedule of cash flows

Plenty of material for future blog posts there, I think – there are lots of functions here that will be very useful. I bet Marco and Alberto are excited…


We now have support for working with Power Query in VBA.

Power Pivot / Power Query Read-Only Connection Problems In Excel 2013 – And What To Do About Them

Anyone who has tried to do any serious work with Power Pivot and Power Query will know about this problem: you use Power Query to load some tables into the Data Model in Excel 2013; you make some changes in the Power Pivot window; you then go back to Power Query, make some changes there and you get the dreaded error

We couldn’t refresh the table ‘xyz’ from the connection ‘Power Query – xyz’. Here’s the error message we got:

COM Error: Microsoft.Mashup.OleDbProvider; The query ‘xyz’ or one of its inputs was modified in Power Query after this connection was added. Please disable and re-enable loading to the Data Model for this query..


This post has a solution for the same problem in Excel 2010, but it doesn’t work for Excel 2013 unfortunately. There is a lot of helpful information out there on the web about this issue if you look around, though, and that’s why I thought it would be useful to bring it all together into one blog post and also pass on some hints and tips about how to recover from this error if you get it. This is the single biggest source of frustration among the Power Query users I speak to; a fix for it is being worked on, and I hope it gets released soon.

Problem Description

Why does this problem occur? Let’s take a simple repro.

  1. Import the data from a table in SQL Server using Power Query. Load it into the Excel Data Model.
  2. Open the PowerPivot window in Excel, then create measures/calculated fields, calculated columns, relationships with other tables as usual.
  3. Go back to the worksheet and build a PivotTable from data in this table, using whatever measures or calculated columns you have created.
  4. Go back to the PowerPivot window and rename one of the columns there. The column name change will be reflected in the PivotTable and everything will continue to work.
  5. Re-open the Power Query query editor, and then rename any of the columns in the table (not necessarily the one you changed in the previous step). Close the query editor window and when the query refreshes, bang! you see the error above. The table in the Excel Data Model is unaffected, however, and your PivotTable continues to work – it’s just that now you can’t refresh the data any more…
  6. Do what the error message suggests and change the Load To option on the Power Query query, unchecking the option to load to the Data Model. When you do this, on the very latest build of Power Query, you’ll see a “Possible Data Loss” warning dialog telling you that you’ll lose any customisations you made. Click Continue, and the query will be disabled. The destination table will be deleted from your Excel Data Model and your PivotTable, while it will still show data, will be frozen.
  7. Change the Load To option on the query to load the data into the Excel Data Model again. When you do this, and refresh the data, the table will be recreated in the Excel Data Model. However, your measures, calculated columns and relationships will all be gone. What’s more, although your PivotTable will now work again, any measures or calculated columns you were using in it will also have gone.
  8. Swear loudly at your computer and add all the measures, calculated columns and relationships to your Data Model all over again.

So what exactly happened here? The important step is step 4. As Miguel Llopis of the Power Query team explains here and here, when you make certain changes to a table in the Power Pivot window the connection from your Power Query query to the Excel Data Model goes into ‘read-only’ mode. This then stops Power Query from making any subsequent changes to the structure of the table.

What changes put the connection to the Excel Data Model in ‘read-only’ mode?

Here’s a list of changes (taken from Miguel’s posts that I linked to above) that you can make in the PowerPivot window that put the connection from your query to the Data Model into ‘read-only’ mode:

  • Edit Table Properties
  • Column-level changes: Rename, Data type change, Delete
  • Table-level changes: Rename, Delete
  • Import more tables using Power Pivot Import Wizard
  • Upgrade existing workbook

How can you tell whether my connection is in ‘read-only’ mode?

To find out whether your connection is in ‘read-only’ mode, go to the Data tab in Excel and click on the Connections button. Then, in the Workbook Connections dialog you’ll see the connection from Power Query to the Data Model listed – it will be called something like ‘Power Query – Query1’ and the description will be ‘Connection to the Query1 query in the Data Model’. Select this connection and click on the Properties button. When the Connection Properties dialog opens, go to the Definition tab. If the connection is in read-only mode the properties will be greyed out, and you’ll see the message ‘Some properties cannot be changed because this connection was modified using the PowerPivot Add-In’. If you do see this message, you’re already in trouble!


How to avoid this problem

Avoiding this problem is pretty straightforward: if you’re using Power Query to load data into the Excel Data Model, don’t make any of the changes listed above in the PowerPivot window! Make them in Power Query instead.

How to recover from this problem

But what if your connection is already in ‘read-only’ mode? There is no magic solution, unfortunately, you are going to have to rebuild your model. However there are two things you can do to reduce the amount of pain you have to go through to recreate your model.

First, you can use the DISCOVER_CALC_DEPENDENCY DMV to list out all of your measure and calculated column definitions to a table in Excel. Here’s some more information about the DMV:

To use this, all you need to do is to create a DAX query table in the way Kasper shows at the end of this post, and use the query:

select * from $system.discover_calc_dependency

Secondly, before you disable and re-enable your Power Query query (as in step 6 above), install the OLAP PivotTable Extensions add-in (if you don’t already have it) and use its option to disable auto-refresh on all of your PivotTables, as described here:

Doing this prevents the PivotTables from auto-refreshing when the table is deleted from the Data Model when you disable the Power Query query. This means that they remember all of their references to your measures and calculated columns, so when you have recreated them in your Data Model (assuming that all of the names are still the same) and you re-enable auto-refresh the PivotTables will not have changed at all and will continue to work as before.

[After writing this post, I realised that Barbara Raney covered pretty much the same material in this post: . I probably read that post when it was published and then forgot about it. I usually don’t blog about things that other people have already blogged about, but since I’d already done the hard work and the tip on using OLAP PivotTable Extensions is new, I thought I’d post anyway. Apologies…]

UPDATE: this problem is now fixed with the following Excel updates: