Finding Minimum Date and Maximum Date Across All Tables in Power Query in Power BI and Excel

Finding Minimum Date and Maximum Date Across All Tables in Power Query in Power BI and Excel

When we talk about data analysis in Power BI, creating a Date table is inevitable. There are different methods to create a Date table either in DAX or in Power Query. In DAX you my use either CALENDAR() function or CALENDARAUTO() function to create the Date table. In Power Query you may use a combination of List.Dates()#date() and #duration() functions. Either way, there is one point that is always challenging and it is how to find out a proper date range, starting from a date in the past and ending with a date in the future, that covers all relevant dates within the data model. One simple answer is, we can ask the business. The SMEs know what the valid date range is..

While this is a correct argument it is not always the case. Especially with the Start Date which is a date in the past. In many cases the business says:

Lets’s have a look at the data to find out.

That is also a correct point, we can always a look at the data, find all columns with either Date or DateTime datatypes then sort the data in ascending or descending order to get the results. But what if there many of them? Then this process can be very time consuming.

Many of you may already thought that we can use CALENDARAUTO() in DAX and we are good to go. Well, that’s not quite right. In many cases there are some Date or DateTime columns that must not be considered in our Date dimension. Like Birth Date or Deceased Date. More on this later in this post.

In this post I share a piece of code I wrote for myself. I was in a situation to identify the Start Date and the End Date of the date dimension many times, so I thought it might help you as well.

How it works?

The Power Query expressions I share in this post starts with getting all existing queries using:

  • #sections intrinsic variable
  • Filtering out the current query name, which is GetMinMaxAllDates in my sample, to avoid getting the following error:

Expression.Error: A cyclic reference was encountered during evaluation.

Expression.Error: A cyclic reference was encountered during evaluation.
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Power BI Ecosystem Report Authoring Tools Demystified

Power BI Reporting Tools Confusion

There are a lot of discussions these days around Power BI tools to create reports and for sure many of you may have already downloaded and worked with some of them if not all of them. You may also already thought that some of the tools’ names are confusingly similar. I recently had an interesting conversation with fellow who has a lot of SSRS report writing background. I was talking about Paginated reports and said, I downloaded the latest version of Power BI Report Builder… that he immediately said, wait a second…

  • John: Power BI Report Builder? Oh I see, that’s the one that you can create paginated reports with then you can deploy those reports into an SSRS instance.
  • me: NOPE! That’s not the case I’m afraid.
  • John: Oh I know, I meant Power BI Report Server, you can deploy the reports to an instance of Power BI Report Server. I knew it!
  • me: NO! That’s not what I’m talking about…
  • John: What the…?

I bet some of you had similar conversation with a friend or a customer. OK, in this post I explain a little bit about report authoring tools available to you and your organisation to get the most out of your Power BI ecosystem.

Here is a list of all reporting tools currently available to you:

  • Power BI Service: It is a SaaS (Software as a Service) offering from Microsoft in the cloud. The users in an organisation, based on their access rights, may be able to create and publish data, reports, dashboards in Power BI Service. The users can also schedule data refreshes on the published data as well as securely sharing and distributing the contents. While creating or editing reports is possible in Power BI Service, it is strongly recommended to avoid this method for several reasons. The most obvious one is that the changes you make in a report may be soon get overwritten by someone else that republishes the same report from Power BI Desktop. Check this blog post from SQLChick to see why you should avoid creating or editing reports directly from Power BI Service. The reports are downloadable in PBIX format. Use Power BI Service here.
  • Power BI Desktop: It is a desktop report authoring tool that can be used to connect to, or loading data from, varies types of data sources, preparing, transforming and cleansing that data and at last visualising the data. Power BI Desktop is the predominant report authoring tool with a lot more functionalities and flexibility than Power BI Service. For instance, setting up Role Level Security (RLS) is NOT available in Power BI Service. The format of the report file is PBIX. Download Power BI Desktop from here.
  • Power BI Report Builder (Paginated): Paginated reports aka “pixel perfect reports”, as the name resembles, are formatted in a way to fit perfectly on a page. That report page might later be printed. You have exact control over the page formatting to display your data in tables or charts. The reports are not as interactive as Power BI Desktop reports are. Paginated reports are based on RDL technology which is standard report format in SQL Server Reporting Services. The tool for developing paginated report in Power BI ecosystem is Power BI Report Builder. The reports file type is RDL. You can currently publish Paginated reports only to a Workspace that is backed with a premium capacity. Download Power BI Report Builder from here.
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