Forum Discussion
Incorrect Power BI Dynamic Previous Period Calculation
I have a date slicer to control and update all the KPI ratios in my visual. When I choose a certain date range, one of my KPI ratios should show the total count within my selected date range (e.g Start: 2020-07-04, End: 2020-07-31). Another ratio should be showing the same period before (e.g Start: 2020-06-07, End: 2020-07-04). But in my current situation, I see both ratios are the same (current vs previous). Here is my DAX calculation for the previous period ratio
num_num_in_Previous_Period =
VAR
num_Start_Period = MIN(SN_Incident[sys_created_on])
VAR
num_End_Period = MAX(SN_Incident[sys_created_on])
var
num_Period_Diff = DATEDIFF( num_Start_Period, num_End_Period, DAY)
VAR
num_End_of_Previous_Period = num_Start_Period
VAR
num_Start_of_Previous_Period = num_End_of_Previous_Period - num_Period_Diff
RETURN
CALCULATE( SUM(SN_Incident[num]), FILTER(SN_Incident, num_Start_of_Previous_Period <= SN_Incident[sys_created_on])) 7
// Such calculations should be performed with // a Date table in the model. I suspect your // model consists of one big table, right? // If this is the case, then please be aware // that you're not doing it right. To know // how to correctly model data in Power BI // please read upon dimensional modeling or // watch some YT videos where such things // are discussed at length. If you don't follow // Best Practices, be prepared for some nasty // bugs that you'll not even be able to // diagnose. You'll not even be aware that // they exist. // But here's the measure you're asking for // in this "dirty" model: [Your Measure] = VAR __start = MIN( SN_Incident[sys_created_on] ) VAR __end = MAX( SN_Incident[sys_created_on] ) VAR __dayDiff = DATEDIFF( __start, __end, DAY ) VAR __endPrev = __start VAR __startPrev = __endPrev - __dayDiff VAR __result = CALCULATE( SUM( SN_Incident[num] ), __startPrev <= SN_Incident[sys_created_on], SN_Incident[sys_created_on] <= __endPrev ) RETURN __result
2 Replies
- Greg_Deckler
Community Champion
Not really enough information to go on, please first check if your issue is a common issue listed here: https://community.powerbi.com/t5/Community-Blog/Before-You-Post-Read-This/ba-p/1116882
Also, please see this post regarding How to Get Your Question Answered Quickly: https://community.powerbi.com/t5/Community-Blog/How-to-Get-Your-Question-Answered-Quickly/ba-p/38490
The most important parts are:
1. Sample data as text, use the table tool in the editing bar
2. Expected output from sample data
3. Explanation in words of how to get from 1. to 2. // Such calculations should be performed with // a Date table in the model. I suspect your // model consists of one big table, right? // If this is the case, then please be aware // that you're not doing it right. To know // how to correctly model data in Power BI // please read upon dimensional modeling or // watch some YT videos where such things // are discussed at length. If you don't follow // Best Practices, be prepared for some nasty // bugs that you'll not even be able to // diagnose. You'll not even be aware that // they exist. // But here's the measure you're asking for // in this "dirty" model: [Your Measure] = VAR __start = MIN( SN_Incident[sys_created_on] ) VAR __end = MAX( SN_Incident[sys_created_on] ) VAR __dayDiff = DATEDIFF( __start, __end, DAY ) VAR __endPrev = __start VAR __startPrev = __endPrev - __dayDiff VAR __result = CALCULATE( SUM( SN_Incident[num] ), __startPrev <= SN_Incident[sys_created_on], SN_Incident[sys_created_on] <= __endPrev ) RETURN __result
