Microsoft Power BI is an interactive data visualization software product developed by Microsoft with a primary focus on business intelligence. It is part of the Microsoft Power Platform. Power BI is a collection of software services, apps, and connectors that work together to turn various sources of data into static and interactive data visualizations. Data may be input by reading directly from a database, webpage, PDF, or structured files such as spreadsheets, CSV, XML, JSON, XLSX, and SharePoint.

A Business Case: New/Lost/Returning Customers

New Customers = 
var _currdate=MAX('Calendar Lookup'[Transaction_Date].[Date])
var _salesthisperiod=[Sales per period]
var _customers=
ADDCOLUMNS(
    'Customer Lookup',
    "Sales Until Now",
    CALCULATE(
        [Sales per period],
    DATESINPERIOD(
        'Calendar Lookup'[Transaction_Date].[Date],
        _currdate,
        -1*[Period Value],
        MONTH)),
    "Running Total Sales",
    [Running Total of Sales]
)
var _newcustomers=
FILTER(_customers,
[Running Total Sales]=[Sales Until Now] &&
[Sales Until Now]>0)
return
if(_salesthisperiod>0,
COUNTROWS(_newcustomers))

Lost Customers = 
var _currdate=MAX('Calendar Lookup'[Transaction_Date].[Date])
var _salesthisperiod=[Sales per period]
var _customers=
ADDCOLUMNS(
    'Customer Lookup',
    "Sales Until Now",
    CALCULATE(
        [Sales per period],
    DATESINPERIOD(
        'Calendar Lookup'[Transaction_Date].[Date],
        _currdate,
        -1*[Period Value],
        MONTH)),
    "Running Total Sales",
    [Running Total of Sales]
)
var _lostcustomers=
FILTER(_customers,
[Running Total Sales]>0 && [Sales Until Now]=0)
return
if(_salesthisperiod>0,
COUNTROWS(_lostcustomers)
)

Returning Customers = 
var _currdate=MAX('Calendar Lookup'[Transaction_Date].[Date])
var _salesthisperiod=[Sales per period]
var _customers=
ADDCOLUMNS(
    'Customer Lookup',
    "Sales Until Now",
    CALCULATE(
        [Sales per period],
    DATESINPERIOD(
        'Calendar Lookup'[Transaction_Date].[Date],
        _currdate,
        -1*[Period Value],
        MONTH)),
    "Running Total Sales",
    [Running Total of Sales])
var _returningcustomers=
FILTER(_customers,
[Sales Until Now]>0 && [Sales Until Now]<[Running Total Sales])
return
if(_salesthisperiod>0,
COUNTROWS(_returningcustomers))