Using SQL server temporal tables in power bi for monthly data

0
votes

The goal is to prepare a power BI report that provides historical data based on month-year selected by the user.

To get data for all available months, I am trying to do something like below 

SELECT * FROM Employee   
    FOR SYSTEM_TIME    
        AS OF <<End of month>>

I want to run this query for every month available in the history table then union them all in a single table.

This way, I will be able to let the user select any month-year in power bi and filter this union table based on the selection.

The only question is that, how do I retrieve all available months from history table of a temporal table, so that I can iterate over them and run the above query for each?

1
sql-serverpowerbisql-server-2016sql-server-2017powerbi-desktop

1 Answers

1
votes

One solution would be to create a view (or even run a select statement) that hard codes all the dates and unions them up. 

SELECT * FROM Employee 
FOR SYSTEM_TIME 
AS OF '2010-01-01'
UNION ALL
SELECT * FROM Employee 
FOR SYSTEM_TIME 
AS OF '2010-02-01'
UNION ALL
SELECT * FROM Employee 
FOR SYSTEM_TIME 
AS OF '2010-03-01'

This is the 'brute force' method.

It's probably possible to do something much smarter in M (the import language in Power BI) but I'm unable to find a good example