Compare text value with previous month

[Junaid11]

Hello,
I want to compare Code which is Text with previous month. Each code can come is unique like in January this code can only comes one not more than that. Same code can come in next month but it can only come only once there as well. 
My tale looks like below:

Month	Code
March	112
March	123
April	866
April	112
May	656
May	234

I want to create a new column and comapre these codes with previous month. If For example code 112 in April is also in previous month then the value against it should be like unchanged. If the codeis not in previous month then it should show new else it should show gone. I am attaching a outcome table as well along with the criteria.

Month	Code	Outcome
March	112	GONE
March	123	GONE
April	866	NEW
April	112	UNCHANGED
May	656	NEW
May	234	NEW

If Exist in March and April: 'Unchanged'
If Exist in March Not Exist April: 'Gone'
if don't exist in march and exist in April: 'New"
It would be highly appreciated if I can get the response.
Thank you

[amitchandak]

@Junaid11 , Try like

New column =
var _date = [Date]
var _code = maxx(filter(Table,eomonth(_date,0) = eomonth([Date],0) ),[Code])
return
Switch(True(),

[Code] = _code, "Unchanged",

Not(isblank(_code)) && [Code]<> _code, "New" , "Gone")

[Junaid11]

Hello @amitchandak ,

The code is not working I am getting below outcome which is not similar to outocme I have mentioned.