Compare 2 rows in same table of PowerBI - powerbi

Question

I am trying to create a column to see if an ID equals another ID with the same month. It should show "NO" but if an ID equals another ID with a different month. It should show "YES". Other show "NO". see as below
ID Month Duplicate
1 4 No
1 4 No
2 5 No
2 6 Yes
2 7 Yes
3 8 No
4 6 No
4 6 No
4 7 Yes
4 8 Yes
5 6 No
5 6 No
5 6 No
My code like this
Duplicate =
IF (
COUNTROWS ( FILTER ( Data, Data[Policy No] = EARLIER( Data[Policy No]) ) )
> 1
&& COUNTROWS ( FILTER ( Data, Data[Month] < EARLIER(Data[Month]) ) ),
"YES",
"NO")
but it is not correct because when I select the first month as month 4 it shows no but when I select month 5 it shows yes. Like as below
ID month Duplicate
1 4 No
1 4 No
2 5 Yes
2 5 Yes
Please help me resolve this
Thank you

Answer 1

Not sure I understand the logic you want to implement but i THINK this will do what you're looking for (providing I did understand...).
I prefer to use variables rather than the EARLIER function. IMHO it makes the code easier to understand and more readable, especially for others.
This is a calculated column in your 'Data' table
Check =
var _id = [ID]
var _month = [Month]
var _check_both =
CALCULATE(
COUNTROWS('Data'),
FILTER(
ALL('Data'),
'Data'[ID] = _id && 'Data'[Month] = _month
)
)
var _check_id =
CALCULATE(
COUNTROWS('Data'),
FILTER(
ALL('Data'),
'Data'[ID] = _id
)
)
return
SWITCH(
TRUE(),
_check_both > 1, "No",
_check_id > 1, "Yes",
"NO"
)