Once we discuss information evaluation in Energy BI, making a Date desk is inevitable. There are totally different strategies to create a Date desk both in DAX or in Energy Question. In DAX you my use both CALENDAR() operate or CALENDARAUTO() operate to create the Date desk. In Energy Question it’s possible you’ll use a mixture of Checklist.Dates(), #date() and #period() capabilities. Both manner, there’s one level that’s all the time difficult and it’s tips on how to discover out a correct date vary, ranging from a date prior to now and ending with a date sooner or later, that covers all related dates throughout the information mannequin. One easy reply is, we are able to ask the enterprise. The SMEs know what the legitimate date vary is..

Whereas this can be a right argument it’s not all the time the case. Particularly with the Begin Date which is a date prior to now. In lots of circumstances the enterprise says:

Lets’s take a look on the information to seek out out.

That can be an accurate level, we are able to all the time a have a look at the info, discover all columns with both Date or DateTime datatypes then type the info in ascending or descending order to get the outcomes. However what if there a lot of them? Then this course of will be very time consuming.

Lots of it’s possible you’ll already thought that we are able to use CALENDARAUTO() in DAX and we’re good to go. Effectively, that’s not fairly proper. In lots of circumstances there are some Date or DateTime columns that should not be thought-about in our Date dimension. Like Delivery Date or Deceased Date. Extra on this later on this publish.

On this publish I share a chunk of code I wrote for myself. I used to be in a state of affairs to determine the Begin Date and the Finish Date of the date dimension many instances, so I assumed it’d make it easier to as nicely.

The Energy Question expressions I share on this publish begins with getting all current queries utilizing:

• #sections intrinsic variable
• Filtering out the present question identify, which is GetMinMaxAllDates in my pattern, to keep away from getting the next error:

Expression.Error: A cyclic reference was encountered throughout analysis.

• Filtering out the queries which can be NOT as kind desk
• Including a brand new structured column named TableSchema that features the tables’ construction
• Increasing the TableSchema structured column preserving the Title and Form columns and renaming the Title column to Column Title and the Form column to Datatype
• Filter the outcomes to maintain solely the columns with both Date or DateTime datatypes
• Filtering out pointless values from the Column Title like Delivery Date
• Including a brand new column named Min Date that will get the minimal worth of the column that seems within the Column Title column of the desk worth that seems within the Worth column

Hmm! I suppose it’s an excessive amount of mentioning worth, column and desk in numerous contexts. I hope I’m not making it much more complicated although.

• Including one other new column named Max Date much like how we created the Min Date
• Extracting the minimal worth of the Min Date column
• Extracting the utmost values of the Max Date column
• Displaying the latter two as a listing

So in case you are in search of an answer right here is the Energy Question expressions that I take advantage of:

let
    AllQueries = #sections,
    RecordToTable = File.ToTable(AllQueries[Section1]),
    FilterOutCurrentQuery = Desk.SelectRows(RecordToTable, every [Name] <> "GetMinMaxAllDates" and Kind.Is(Worth.Kind([Value]), kind desk) = true),
    AddTableSchemaColumn = Desk.AddColumn(FilterOutCurrentQuery, "TableSchema", every attempt Desk.Schema([Value]) in any other case null),
    ExpandTableSchema = Desk.Buffer(Desk.ExpandTableColumn(AddTableSchemaColumn, "TableSchema", {"Title", "Form"}, {"Column Title", "Datatype"})),
    FilterTypes = Desk.SelectRows(ExpandTableSchema, every ([Datatype] = "datetime" or [Datatype] = "date")),
    AddedMinDateColumn = Desk.AddColumn(FilterTypes, "Min Date", every Date.From(Checklist.Min(Desk.Column([Value], [Column Name])))),
    AddedMaxDateColumn = Desk.AddColumn(AddedMinDateColumn, "Max Date", every Date.From(Checklist.Max(Desk.Column([Value], [Column Name])))),
    FilterOutUnnecessaryColumns = Desk.SelectRows(AddedMaxDateColumn, every ([Column Name] <> "BirthDate")),
    MinDate = Checklist.Min(Checklist.Mix({FilterOutUnnecessaryColumns[Min Date], FilterOutUnnecessaryColumns[Max Date]})),
    MaxDate = Checklist.Max(Checklist.Mix({FilterOutUnnecessaryColumns[Min Date], FilterOutUnnecessaryColumns[Max Date]})),
    MinMaxDates = {"Min Date = " & Textual content.From(MinDate), "Max Date = " & Textual content.From(MaxDate)}
in
        MinMaxDates

You’ll be able to obtain the above expressions from right here.

The picture under illustrates the outcomes of operating the above code in Energy Question Editor having 11 reality tables and 2 dimension tables. These tables have 17 columns with both Date or DateTime datatypes:

Observe: As soon as once more, it is advisable to go the present question identify within the expressions above. In my case the present question identify is GetMinMaxAllDates as proven within the picture under:

Earlier on this publish I discussed that in lots of circumstances we do NOT need all Date or DateTime columns to be lined by the Date desk. A very good instance for it’s Delivery Date and Deceased Date. If we don’t notice that then we are able to create lots of irrelevant dates in our Date desk like what we get because the Min Date within the above picture which is 10/02/1916. As you’ll be able to within the picture above there’s a FilterOutUnnecessaryColumns step. We click on on that step to filter the pointless values from the Column Title column as proven within the picture under:

Click on on the final step which is MinMaxDates to see the brand new values as proven within the picture under:

By operating the above question you get the legitimate date vary, so now you can create a Date desk with any technique of selection, both in Energy Question or DAX utilizing the above date vary. Bear in mind, creating the Date desk is totally separate course of. This question is barely serving to us discovering minimal and most legitimate dates throughout all tables loaded into the Energy Question Editor.

Concerns

• The above tables altogether have 40M rows and the GetMinMaxAllDates question ran in roughly 10 sec on my machine which isn’t dangerous in any respect. Nevertheless, in bigger tables it might take extra to provide the outcomes
• You need to have some queries already loaded into the Energy BI Editor
• This technique additionally works in Direct Question mode, however you anticipate the question to take extra time to get the outcomes
• The above question retrieves the min date and max date throughout all tables. Whenever you create a Date desk, remember that the Date column ought to begin from the 1st Jan of the min date going all the best way as much as the thirty first Dec of the max date
• This technique works in Energy BI Desktop RS
• This technique is NOT supported in Energy BI Dataflows

Get pleasure from your Relationship!